diff --git a/fhir-model/FHIRPath.g4 b/fhir-model/FHIRPath.g4
index e7a9b3d7702..f8820c57e88 100644
--- a/fhir-model/FHIRPath.g4
+++ b/fhir-model/FHIRPath.g4
@@ -1,6 +1,7 @@
 grammar FHIRPath;
 
 // Grammar rules
+// [FHIRPath](http://hl7.org/fhirpath/N1) Normative Release
 
 //prog: line (line)*;
 //line: ID ( '(' expr ')') ':' expr '\r'? '\n';
@@ -35,13 +36,14 @@ literal
         | ('true' | 'false')                                    #booleanLiteral
         | STRING                                                #stringLiteral
         | NUMBER                                                #numberLiteral
+        | DATE                                                  #dateLiteral
         | DATETIME                                              #dateTimeLiteral
         | TIME                                                  #timeLiteral
         | quantity                                              #quantityLiteral
         ;
 
 externalConstant
-        : '%' identifier
+        : '%' ( identifier | STRING )
         ;
 
 invocation                          // Terms that can be used after the function/member invocation '.'
@@ -90,6 +92,8 @@ identifier
         : IDENTIFIER
         | DELIMITEDIDENTIFIER
         | 'as'
+        | 'contains'
+        | 'in'
         | 'is'
         ;
 
@@ -98,40 +102,34 @@ identifier
     Lexical rules
 *****************************************************************/
 
-// Not sure why, but with these as lexical rules, when the grammar is imported into CQL, they are not correctly recognized
-// Moving the same rules into the literal production rule above corrects the issue
-//EMPTY
-//        : '{' '}'
-//        ;                      // To create an empty array (and avoid a NULL literal)
+/*
+NOTE: The goal of these rules in the grammar is to provide a date
+token to the parser. As such it is not attempting to validate that
+the date is a correct date, that task is for the parser or interpreter.
+*/
 
-//BOOL
-//        : 'true'
-//        | 'false'
-//        ;
+DATE
+        : '@' DATEFORMAT
+        ;
 
 DATETIME
-        : '@'
-            [0-9][0-9][0-9][0-9] // year
-            (
-                '-'[0-9][0-9] // month
-                (
-                    '-'[0-9][0-9] // day
-                    (
-                        'T' TIMEFORMAT
-                    )?
-                 )?
-             )?
-             'Z'? // UTC specifier
+        : '@' DATEFORMAT 'T' (TIMEFORMAT TIMEZONEOFFSETFORMAT?)?
         ;
 
 TIME
         : '@' 'T' TIMEFORMAT
         ;
 
+fragment DATEFORMAT
+        : [0-9][0-9][0-9][0-9] ('-'[0-9][0-9] ('-'[0-9][0-9])?)?
+        ;
+
 fragment TIMEFORMAT
-        :
-            [0-9][0-9] (':'[0-9][0-9] (':'[0-9][0-9] ('.'[0-9]+)?)?)?
-            ('Z' | ('+' | '-') [0-9][0-9]':'[0-9][0-9])? // timezone
+        : [0-9][0-9] (':'[0-9][0-9] (':'[0-9][0-9] ('.'[0-9]+)?)?)?
+        ;
+
+fragment TIMEZONEOFFSETFORMAT
+        : ('Z' | ('+' | '-') [0-9][0-9]':'[0-9][0-9])
         ;
 
 IDENTIFIER
diff --git a/fhir-model/pom.xml b/fhir-model/pom.xml
index f448e7461c0..2559b55a5ce 100644
--- a/fhir-model/pom.xml
+++ b/fhir-model/pom.xml
@@ -18,7 +18,7 @@
         <dependency>
             <groupId>org.antlr</groupId>
             <artifactId>antlr4-runtime</artifactId>
-            <version>4.5.3</version>
+            <version>4.7.2</version>
         </dependency>
         <dependency>
             <groupId>net.jcip</groupId>
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPath.interp b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPath.interp
new file mode 100644
index 00000000000..fcda0d2c8f9
--- /dev/null
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPath.interp
@@ -0,0 +1,153 @@
+token literal names:
+null
+'.'
+'['
+']'
+'+'
+'-'
+'*'
+'/'
+'div'
+'mod'
+'&'
+'is'
+'as'
+'|'
+'<='
+'<'
+'>'
+'>='
+'='
+'~'
+'!='
+'!~'
+'in'
+'contains'
+'and'
+'or'
+'xor'
+'implies'
+'('
+')'
+'{'
+'}'
+'true'
+'false'
+'%'
+'$this'
+'$index'
+'$total'
+','
+'year'
+'month'
+'week'
+'day'
+'hour'
+'minute'
+'second'
+'millisecond'
+'years'
+'months'
+'weeks'
+'days'
+'hours'
+'minutes'
+'seconds'
+'milliseconds'
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+
+token symbolic names:
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+DATE
+DATETIME
+TIME
+IDENTIFIER
+DELIMITEDIDENTIFIER
+STRING
+NUMBER
+WS
+COMMENT
+LINE_COMMENT
+
+rule names:
+expression
+term
+literal
+externalConstant
+invocation
+function
+paramList
+quantity
+unit
+dateTimePrecision
+pluralDateTimePrecision
+typeSpecifier
+qualifiedIdentifier
+identifier
+
+
+atn:
+[3, 24715, 42794, 33075, 47597, 16764, 15335, 30598, 22884, 3, 66, 152, 4, 2, 9, 2, 4, 3, 9, 3, 4, 4, 9, 4, 4, 5, 9, 5, 4, 6, 9, 6, 4, 7, 9, 7, 4, 8, 9, 8, 4, 9, 9, 9, 4, 10, 9, 10, 4, 11, 9, 11, 4, 12, 9, 12, 4, 13, 9, 13, 4, 14, 9, 14, 4, 15, 9, 15, 3, 2, 3, 2, 3, 2, 3, 2, 5, 2, 35, 10, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 7, 2, 75, 10, 2, 12, 2, 14, 2, 78, 11, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 5, 3, 87, 10, 3, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 5, 4, 98, 10, 4, 3, 5, 3, 5, 3, 5, 5, 5, 103, 10, 5, 3, 6, 3, 6, 3, 6, 3, 6, 3, 6, 5, 6, 110, 10, 6, 3, 7, 3, 7, 3, 7, 5, 7, 115, 10, 7, 3, 7, 3, 7, 3, 8, 3, 8, 3, 8, 7, 8, 122, 10, 8, 12, 8, 14, 8, 125, 11, 8, 3, 9, 3, 9, 5, 9, 129, 10, 9, 3, 10, 3, 10, 3, 10, 5, 10, 134, 10, 10, 3, 11, 3, 11, 3, 12, 3, 12, 3, 13, 3, 13, 3, 14, 3, 14, 3, 14, 7, 14, 145, 10, 14, 12, 14, 14, 14, 148, 11, 14, 3, 15, 3, 15, 3, 15, 2, 3, 2, 16, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 2, 14, 3, 2, 6, 7, 3, 2, 8, 11, 4, 2, 6, 7, 12, 12, 3, 2, 16, 19, 3, 2, 20, 23, 3, 2, 24, 25, 3, 2, 27, 28, 3, 2, 13, 14, 3, 2, 34, 35, 3, 2, 41, 48, 3, 2, 49, 56, 5, 2, 13, 14, 24, 25, 60, 61, 2, 171, 2, 34, 3, 2, 2, 2, 4, 86, 3, 2, 2, 2, 6, 97, 3, 2, 2, 2, 8, 99, 3, 2, 2, 2, 10, 109, 3, 2, 2, 2, 12, 111, 3, 2, 2, 2, 14, 118, 3, 2, 2, 2, 16, 126, 3, 2, 2, 2, 18, 133, 3, 2, 2, 2, 20, 135, 3, 2, 2, 2, 22, 137, 3, 2, 2, 2, 24, 139, 3, 2, 2, 2, 26, 141, 3, 2, 2, 2, 28, 149, 3, 2, 2, 2, 30, 31, 8, 2, 1, 2, 31, 35, 5, 4, 3, 2, 32, 33, 9, 2, 2, 2, 33, 35, 5, 2, 2, 13, 34, 30, 3, 2, 2, 2, 34, 32, 3, 2, 2, 2, 35, 76, 3, 2, 2, 2, 36, 37, 12, 12, 2, 2, 37, 38, 9, 3, 2, 2, 38, 75, 5, 2, 2, 13, 39, 40, 12, 11, 2, 2, 40, 41, 9, 4, 2, 2, 41, 75, 5, 2, 2, 12, 42, 43, 12, 9, 2, 2, 43, 44, 7, 15, 2, 2, 44, 75, 5, 2, 2, 10, 45, 46, 12, 8, 2, 2, 46, 47, 9, 5, 2, 2, 47, 75, 5, 2, 2, 9, 48, 49, 12, 7, 2, 2, 49, 50, 9, 6, 2, 2, 50, 75, 5, 2, 2, 8, 51, 52, 12, 6, 2, 2, 52, 53, 9, 7, 2, 2, 53, 75, 5, 2, 2, 7, 54, 55, 12, 5, 2, 2, 55, 56, 7, 26, 2, 2, 56, 75, 5, 2, 2, 6, 57, 58, 12, 4, 2, 2, 58, 59, 9, 8, 2, 2, 59, 75, 5, 2, 2, 5, 60, 61, 12, 3, 2, 2, 61, 62, 7, 29, 2, 2, 62, 75, 5, 2, 2, 4, 63, 64, 12, 15, 2, 2, 64, 65, 7, 3, 2, 2, 65, 75, 5, 10, 6, 2, 66, 67, 12, 14, 2, 2, 67, 68, 7, 4, 2, 2, 68, 69, 5, 2, 2, 2, 69, 70, 7, 5, 2, 2, 70, 75, 3, 2, 2, 2, 71, 72, 12, 10, 2, 2, 72, 73, 9, 9, 2, 2, 73, 75, 5, 24, 13, 2, 74, 36, 3, 2, 2, 2, 74, 39, 3, 2, 2, 2, 74, 42, 3, 2, 2, 2, 74, 45, 3, 2, 2, 2, 74, 48, 3, 2, 2, 2, 74, 51, 3, 2, 2, 2, 74, 54, 3, 2, 2, 2, 74, 57, 3, 2, 2, 2, 74, 60, 3, 2, 2, 2, 74, 63, 3, 2, 2, 2, 74, 66, 3, 2, 2, 2, 74, 71, 3, 2, 2, 2, 75, 78, 3, 2, 2, 2, 76, 74, 3, 2, 2, 2, 76, 77, 3, 2, 2, 2, 77, 3, 3, 2, 2, 2, 78, 76, 3, 2, 2, 2, 79, 87, 5, 10, 6, 2, 80, 87, 5, 6, 4, 2, 81, 87, 5, 8, 5, 2, 82, 83, 7, 30, 2, 2, 83, 84, 5, 2, 2, 2, 84, 85, 7, 31, 2, 2, 85, 87, 3, 2, 2, 2, 86, 79, 3, 2, 2, 2, 86, 80, 3, 2, 2, 2, 86, 81, 3, 2, 2, 2, 86, 82, 3, 2, 2, 2, 87, 5, 3, 2, 2, 2, 88, 89, 7, 32, 2, 2, 89, 98, 7, 33, 2, 2, 90, 98, 9, 10, 2, 2, 91, 98, 7, 62, 2, 2, 92, 98, 7, 63, 2, 2, 93, 98, 7, 57, 2, 2, 94, 98, 7, 58, 2, 2, 95, 98, 7, 59, 2, 2, 96, 98, 5, 16, 9, 2, 97, 88, 3, 2, 2, 2, 97, 90, 3, 2, 2, 2, 97, 91, 3, 2, 2, 2, 97, 92, 3, 2, 2, 2, 97, 93, 3, 2, 2, 2, 97, 94, 3, 2, 2, 2, 97, 95, 3, 2, 2, 2, 97, 96, 3, 2, 2, 2, 98, 7, 3, 2, 2, 2, 99, 102, 7, 36, 2, 2, 100, 103, 5, 28, 15, 2, 101, 103, 7, 62, 2, 2, 102, 100, 3, 2, 2, 2, 102, 101, 3, 2, 2, 2, 103, 9, 3, 2, 2, 2, 104, 110, 5, 28, 15, 2, 105, 110, 5, 12, 7, 2, 106, 110, 7, 37, 2, 2, 107, 110, 7, 38, 2, 2, 108, 110, 7, 39, 2, 2, 109, 104, 3, 2, 2, 2, 109, 105, 3, 2, 2, 2, 109, 106, 3, 2, 2, 2, 109, 107, 3, 2, 2, 2, 109, 108, 3, 2, 2, 2, 110, 11, 3, 2, 2, 2, 111, 112, 5, 28, 15, 2, 112, 114, 7, 30, 2, 2, 113, 115, 5, 14, 8, 2, 114, 113, 3, 2, 2, 2, 114, 115, 3, 2, 2, 2, 115, 116, 3, 2, 2, 2, 116, 117, 7, 31, 2, 2, 117, 13, 3, 2, 2, 2, 118, 123, 5, 2, 2, 2, 119, 120, 7, 40, 2, 2, 120, 122, 5, 2, 2, 2, 121, 119, 3, 2, 2, 2, 122, 125, 3, 2, 2, 2, 123, 121, 3, 2, 2, 2, 123, 124, 3, 2, 2, 2, 124, 15, 3, 2, 2, 2, 125, 123, 3, 2, 2, 2, 126, 128, 7, 63, 2, 2, 127, 129, 5, 18, 10, 2, 128, 127, 3, 2, 2, 2, 128, 129, 3, 2, 2, 2, 129, 17, 3, 2, 2, 2, 130, 134, 5, 20, 11, 2, 131, 134, 5, 22, 12, 2, 132, 134, 7, 62, 2, 2, 133, 130, 3, 2, 2, 2, 133, 131, 3, 2, 2, 2, 133, 132, 3, 2, 2, 2, 134, 19, 3, 2, 2, 2, 135, 136, 9, 11, 2, 2, 136, 21, 3, 2, 2, 2, 137, 138, 9, 12, 2, 2, 138, 23, 3, 2, 2, 2, 139, 140, 5, 26, 14, 2, 140, 25, 3, 2, 2, 2, 141, 146, 5, 28, 15, 2, 142, 143, 7, 3, 2, 2, 143, 145, 5, 28, 15, 2, 144, 142, 3, 2, 2, 2, 145, 148, 3, 2, 2, 2, 146, 144, 3, 2, 2, 2, 146, 147, 3, 2, 2, 2, 147, 27, 3, 2, 2, 2, 148, 146, 3, 2, 2, 2, 149, 150, 9, 13, 2, 2, 150, 29, 3, 2, 2, 2, 14, 34, 74, 76, 86, 97, 102, 109, 114, 123, 128, 133, 146]
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPath.tokens b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPath.tokens
index 0fe45617b71..38c5116464f 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPath.tokens
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPath.tokens
@@ -52,15 +52,16 @@ T__50=51
 T__51=52
 T__52=53
 T__53=54
-DATETIME=55
-TIME=56
-IDENTIFIER=57
-DELIMITEDIDENTIFIER=58
-STRING=59
-NUMBER=60
-WS=61
-COMMENT=62
-LINE_COMMENT=63
+DATE=55
+DATETIME=56
+TIME=57
+IDENTIFIER=58
+DELIMITEDIDENTIFIER=59
+STRING=60
+NUMBER=61
+WS=62
+COMMENT=63
+LINE_COMMENT=64
 '.'=1
 '['=2
 ']'=3
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathAbstractNode.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathAbstractNode.java
index 33cd2eb1279..2b54929fac7 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathAbstractNode.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathAbstractNode.java
@@ -17,7 +17,7 @@ public abstract class FHIRPathAbstractNode implements FHIRPathNode {
     protected final String name;
     protected final String path;
     protected final FHIRPathType type;
-    protected final FHIRPathPrimitiveValue value;
+    protected final FHIRPathSystemValue value;
     protected final Collection<FHIRPathNode> children;
     
     protected FHIRPathAbstractNode(Builder builder) {
@@ -49,7 +49,7 @@ public boolean hasValue() {
     }
     
     @Override
-    public FHIRPathPrimitiveValue getValue() {
+    public FHIRPathSystemValue getValue() {
         return value;
     }
     
@@ -87,7 +87,7 @@ public static abstract class Builder implements FHIRPathNode.Builder {
         // optional
         protected String name;
         protected String path;
-        protected FHIRPathPrimitiveValue value;
+        protected FHIRPathSystemValue value;
         protected Collection<FHIRPathNode> children = new ArrayList<>();
         
         protected Builder(FHIRPathType type) {
@@ -108,7 +108,7 @@ public Builder path(String path) {
         }
         
         @Override
-        public Builder value(FHIRPathPrimitiveValue value) {
+        public Builder value(FHIRPathSystemValue value) {
             children.remove(this.value);
             this.value = value;
             children.add(this.value);
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathBaseVisitor.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathBaseVisitor.java
index 76ae4bc1f88..e01099c8aa0 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathBaseVisitor.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathBaseVisitor.java
@@ -1,498 +1,301 @@
-/*
- * (C) Copyright IBM Corp. 2019
- *
- * SPDX-License-Identifier: Apache-2.0
- */
-
+// Generated from FHIRPath.g4 by ANTLR 4.7.2
 package com.ibm.fhir.model.path;
-
 import org.antlr.v4.runtime.tree.AbstractParseTreeVisitor;
 
 /**
- * This class provides an empty implementation of {@link FHIRPathVisitor}, which can be extended to create a visitor
- * which only needs to handle a subset of the available methods.
+ * This class provides an empty implementation of {@link FHIRPathVisitor},
+ * which can be extended to create a visitor which only needs to handle a subset
+ * of the available methods.
  *
- * @param <T>
- *            The return type of the visit operation. Use {@link Void} for operations with no return type.
+ * @param <T> The return type of the visit operation. Use {@link Void} for
+ * operations with no return type.
  */
 public class FHIRPathBaseVisitor<T> extends AbstractParseTreeVisitor<T> implements FHIRPathVisitor<T> {
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitIndexerExpression(FHIRPathParser.IndexerExpressionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitIndexerExpression(FHIRPathParser.IndexerExpressionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitPolarityExpression(FHIRPathParser.PolarityExpressionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitPolarityExpression(FHIRPathParser.PolarityExpressionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitAdditiveExpression(FHIRPathParser.AdditiveExpressionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitAdditiveExpression(FHIRPathParser.AdditiveExpressionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitMultiplicativeExpression(FHIRPathParser.MultiplicativeExpressionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitMultiplicativeExpression(FHIRPathParser.MultiplicativeExpressionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitUnionExpression(FHIRPathParser.UnionExpressionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitUnionExpression(FHIRPathParser.UnionExpressionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitOrExpression(FHIRPathParser.OrExpressionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitOrExpression(FHIRPathParser.OrExpressionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitAndExpression(FHIRPathParser.AndExpressionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitAndExpression(FHIRPathParser.AndExpressionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitMembershipExpression(FHIRPathParser.MembershipExpressionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitMembershipExpression(FHIRPathParser.MembershipExpressionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitInequalityExpression(FHIRPathParser.InequalityExpressionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitInequalityExpression(FHIRPathParser.InequalityExpressionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitInvocationExpression(FHIRPathParser.InvocationExpressionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitInvocationExpression(FHIRPathParser.InvocationExpressionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitEqualityExpression(FHIRPathParser.EqualityExpressionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitEqualityExpression(FHIRPathParser.EqualityExpressionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitImpliesExpression(FHIRPathParser.ImpliesExpressionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitImpliesExpression(FHIRPathParser.ImpliesExpressionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitTermExpression(FHIRPathParser.TermExpressionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitTermExpression(FHIRPathParser.TermExpressionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitTypeExpression(FHIRPathParser.TypeExpressionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitTypeExpression(FHIRPathParser.TypeExpressionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitInvocationTerm(FHIRPathParser.InvocationTermContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitInvocationTerm(FHIRPathParser.InvocationTermContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitLiteralTerm(FHIRPathParser.LiteralTermContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitLiteralTerm(FHIRPathParser.LiteralTermContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitExternalConstantTerm(FHIRPathParser.ExternalConstantTermContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitExternalConstantTerm(FHIRPathParser.ExternalConstantTermContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitParenthesizedTerm(FHIRPathParser.ParenthesizedTermContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitParenthesizedTerm(FHIRPathParser.ParenthesizedTermContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitNullLiteral(FHIRPathParser.NullLiteralContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitNullLiteral(FHIRPathParser.NullLiteralContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitBooleanLiteral(FHIRPathParser.BooleanLiteralContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitBooleanLiteral(FHIRPathParser.BooleanLiteralContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitStringLiteral(FHIRPathParser.StringLiteralContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitStringLiteral(FHIRPathParser.StringLiteralContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitNumberLiteral(FHIRPathParser.NumberLiteralContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitNumberLiteral(FHIRPathParser.NumberLiteralContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitDateTimeLiteral(FHIRPathParser.DateTimeLiteralContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitDateLiteral(FHIRPathParser.DateLiteralContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitTimeLiteral(FHIRPathParser.TimeLiteralContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitDateTimeLiteral(FHIRPathParser.DateTimeLiteralContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitQuantityLiteral(FHIRPathParser.QuantityLiteralContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitTimeLiteral(FHIRPathParser.TimeLiteralContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitExternalConstant(FHIRPathParser.ExternalConstantContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitQuantityLiteral(FHIRPathParser.QuantityLiteralContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitMemberInvocation(FHIRPathParser.MemberInvocationContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitExternalConstant(FHIRPathParser.ExternalConstantContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitFunctionInvocation(FHIRPathParser.FunctionInvocationContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitMemberInvocation(FHIRPathParser.MemberInvocationContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitThisInvocation(FHIRPathParser.ThisInvocationContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitFunctionInvocation(FHIRPathParser.FunctionInvocationContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitIndexInvocation(FHIRPathParser.IndexInvocationContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitThisInvocation(FHIRPathParser.ThisInvocationContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitTotalInvocation(FHIRPathParser.TotalInvocationContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitIndexInvocation(FHIRPathParser.IndexInvocationContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitFunction(FHIRPathParser.FunctionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitTotalInvocation(FHIRPathParser.TotalInvocationContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitParamList(FHIRPathParser.ParamListContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitFunction(FHIRPathParser.FunctionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitQuantity(FHIRPathParser.QuantityContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitParamList(FHIRPathParser.ParamListContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitUnit(FHIRPathParser.UnitContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitQuantity(FHIRPathParser.QuantityContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitDateTimePrecision(FHIRPathParser.DateTimePrecisionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitUnit(FHIRPathParser.UnitContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitPluralDateTimePrecision(FHIRPathParser.PluralDateTimePrecisionContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitDateTimePrecision(FHIRPathParser.DateTimePrecisionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitTypeSpecifier(FHIRPathParser.TypeSpecifierContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitPluralDateTimePrecision(FHIRPathParser.PluralDateTimePrecisionContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitQualifiedIdentifier(FHIRPathParser.QualifiedIdentifierContext ctx) {
-        return visitChildren(ctx);
-    }
-
+    @Override public T visitTypeSpecifier(FHIRPathParser.TypeSpecifierContext ctx) { return visitChildren(ctx); }
+    /**
+     * {@inheritDoc}
+     *
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
+     */
+    @Override public T visitQualifiedIdentifier(FHIRPathParser.QualifiedIdentifierContext ctx) { return visitChildren(ctx); }
     /**
      * {@inheritDoc}
      *
-     * <p>
-     * The default implementation returns the result of calling {@link #visitChildren} on {@code ctx}.
-     * </p>
+     * <p>The default implementation returns the result of calling
+     * {@link #visitChildren} on {@code ctx}.</p>
      */
-    @Override
-    public T visitIdentifier(FHIRPathParser.IdentifierContext ctx) {
-        return visitChildren(ctx);
-    }
-}
+    @Override public T visitIdentifier(FHIRPathParser.IdentifierContext ctx) { return visitChildren(ctx); }
+}
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathBooleanValue.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathBooleanValue.java
index 78e66b6faff..f44381196e6 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathBooleanValue.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathBooleanValue.java
@@ -11,7 +11,7 @@
 
 import com.ibm.fhir.model.path.visitor.FHIRPathNodeVisitor;
 
-public class FHIRPathBooleanValue extends FHIRPathAbstractNode implements FHIRPathPrimitiveValue {
+public class FHIRPathBooleanValue extends FHIRPathAbstractNode implements FHIRPathSystemValue {
     public static final FHIRPathBooleanValue TRUE = FHIRPathBooleanValue.booleanValue(true);
     public static final FHIRPathBooleanValue FALSE = FHIRPathBooleanValue.booleanValue(false);
     
@@ -75,7 +75,7 @@ public Builder path(String path) {
         }
         
         @Override
-        public Builder value(FHIRPathPrimitiveValue value) {
+        public Builder value(FHIRPathSystemValue value) {
             return this;
         }
         
@@ -164,7 +164,7 @@ public String toString() {
     }
 
     @Override
-    public <T> void accept(T param, FHIRPathNodeVisitor<T> visitor) {
-        visitor.visit(param, this);
+    public void accept(FHIRPathNodeVisitor visitor) {
+        visitor.visit(this);
     }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathDateTimeValue.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathDateTimeValue.java
index 952073c1c12..dd9f051820b 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathDateTimeValue.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathDateTimeValue.java
@@ -25,7 +25,7 @@
 
 import com.ibm.fhir.model.path.visitor.FHIRPathNodeVisitor;
 
-public class FHIRPathDateTimeValue extends FHIRPathAbstractNode implements FHIRPathPrimitiveValue {
+public class FHIRPathDateTimeValue extends FHIRPathAbstractNode implements FHIRPathTemporalValue {
     private static final DateTimeFormatter DATE_TIME_PARSER_FORMATTER = new DateTimeFormatterBuilder()
             .appendPattern("yyyy")
             .optionalStart()
@@ -44,10 +44,12 @@ public class FHIRPathDateTimeValue extends FHIRPathAbstractNode implements FHIRP
             .toFormatter();
 
     private final TemporalAccessor dateTime;
+    private final Temporal temporal;
     
     protected FHIRPathDateTimeValue(Builder builder) {
         super(builder);
         dateTime = builder.dateTime;
+        temporal = getTemporal(dateTime);
     }
     
     @Override
@@ -63,6 +65,11 @@ public TemporalAccessor dateTime() {
         return dateTime;
     }
     
+    @Override
+    public Temporal temporal() {
+        return temporal;
+    }
+    
     public static FHIRPathDateTimeValue dateTimeValue(String dateTime) {
         return FHIRPathDateTimeValue.builder(DATE_TIME_PARSER_FORMATTER.parseBest(dateTime, ZonedDateTime::from, LocalDate::from, YearMonth::from, Year::from)).build();
     }
@@ -103,7 +110,7 @@ public Builder path(String path) {
         }
         
         @Override
-        public Builder value(FHIRPathPrimitiveValue value) {
+        public Builder value(FHIRPathSystemValue value) {
             return this;
         }
         
@@ -123,15 +130,17 @@ public FHIRPathDateTimeValue build() {
         }
     }
     
-    public FHIRPathDateTimeValue add(FHIRPathQuantityNode quantityNode) {
+    @Override
+    public FHIRPathDateTimeValue add(FHIRPathQuantityValue quantityValue) {
         Temporal temporal = getTemporal(dateTime);
-        TemporalAmount temporalAmount = getTemporalAmount(quantityNode);
+        TemporalAmount temporalAmount = getTemporalAmount(quantityValue);
         return dateTimeValue(getTemporalAccessor(temporal.plus(temporalAmount), dateTime.getClass()));
     }
     
-    public FHIRPathDateTimeValue subtract(FHIRPathQuantityNode quantityNode) {
+    @Override
+    public FHIRPathDateTimeValue subtract(FHIRPathQuantityValue quantityValue) {
         Temporal temporal = getTemporal(dateTime);
-        TemporalAmount temporalAmount = getTemporalAmount(quantityNode);
+        TemporalAmount temporalAmount = getTemporalAmount(quantityValue);
         return dateTimeValue(getTemporalAccessor(temporal.minus(temporalAmount), dateTime.getClass()));
     }
     
@@ -201,7 +210,7 @@ public static void main(String[] args) {
     }
 
     @Override
-    public <T> void accept(T param, FHIRPathNodeVisitor<T> visitor) {
-        visitor.visit(param, this);
+    public void accept(FHIRPathNodeVisitor visitor) {
+        visitor.visit(this);
     }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathDateValue.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathDateValue.java
new file mode 100644
index 00000000000..2598c6ddbd6
--- /dev/null
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathDateValue.java
@@ -0,0 +1,204 @@
+/*
+ * (C) Copyright IBM Corp. 2019
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.ibm.fhir.model.path;
+
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.getTemporal;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.getTemporalAccessor;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.getTemporalAmount;
+
+import java.time.LocalDate;
+import java.time.Year;
+import java.time.YearMonth;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeFormatterBuilder;
+import java.time.temporal.Temporal;
+import java.time.temporal.TemporalAccessor;
+import java.time.temporal.TemporalAmount;
+import java.util.Collection;
+import java.util.Objects;
+
+import com.ibm.fhir.model.path.visitor.FHIRPathNodeVisitor;
+
+public class FHIRPathDateValue extends FHIRPathAbstractNode implements FHIRPathTemporalValue {
+    private static final DateTimeFormatter DATE_PARSER_FORMATTER = new DateTimeFormatterBuilder()
+            .appendPattern("yyyy")
+            .optionalStart()
+                .appendPattern("-MM")
+                .optionalStart()
+                    .appendPattern("-dd")
+                .optionalEnd()
+            .optionalEnd()
+            .toFormatter();
+
+    private final TemporalAccessor date;
+    private final Temporal temporal;
+    
+    protected FHIRPathDateValue(Builder builder) {
+        super(builder);
+        date = builder.date;
+        temporal = getTemporal(date);
+    }
+    
+    @Override
+    public boolean isDateValue() {
+        return true;
+    }
+    
+    public boolean isPartial() {
+        return !(date instanceof LocalDate);
+    }
+    
+    public TemporalAccessor date() {
+        return date;
+    }
+    
+    @Override
+    public Temporal temporal() {
+        return temporal;
+    }
+    
+    public static FHIRPathDateValue dateValue(String date) {
+        return FHIRPathDateValue.builder(DATE_PARSER_FORMATTER.parseBest(date, LocalDate::from, YearMonth::from, Year::from)).build();
+    }
+    
+    public static FHIRPathDateValue dateValue(TemporalAccessor date) {
+        return FHIRPathDateValue.builder(date).build();
+    }
+    
+    public static FHIRPathDateValue dateValue(String name, TemporalAccessor date) {
+        return FHIRPathDateValue.builder(date).name(name).build();
+    }
+
+    @Override
+    public Builder toBuilder() {
+        return new Builder(type, date);
+    }
+    
+    public static Builder builder(TemporalAccessor dateTime) {
+        return new Builder(FHIRPathType.SYSTEM_DATE_TIME, dateTime);
+    }
+    
+    public static class Builder extends FHIRPathAbstractNode.Builder {
+        private final TemporalAccessor date;
+        
+        private Builder(FHIRPathType type, TemporalAccessor dateTime) {
+            super(type);
+            this.date = dateTime;
+        }
+        
+        @Override
+        public Builder name(String name) {
+            return (Builder) super.name(name);
+        }
+        
+        @Override
+        public Builder path(String path) {
+            return (Builder) super.path(path);
+        }
+        
+        @Override
+        public Builder value(FHIRPathSystemValue value) {
+            return this;
+        }
+        
+        @Override
+        public Builder children(FHIRPathNode... children) {
+            return this;
+        }
+        
+        @Override
+        public Builder children(Collection<FHIRPathNode> children) {
+            return this;
+        }
+
+        @Override
+        public FHIRPathDateValue build() {
+            return new FHIRPathDateValue(this);
+        }
+    }
+    
+    @Override
+    public FHIRPathDateValue add(FHIRPathQuantityValue quantityValue) {
+        Temporal temporal = getTemporal(date);
+        TemporalAmount temporalAmount = getTemporalAmount(quantityValue);
+        return dateValue(getTemporalAccessor(temporal.plus(temporalAmount), date.getClass()));
+    }
+    
+    @Override
+    public FHIRPathDateValue subtract(FHIRPathQuantityValue quantityValue) {
+        Temporal temporal = getTemporal(date);
+        TemporalAmount temporalAmount = getTemporalAmount(quantityValue);
+        return dateValue(getTemporalAccessor(temporal.minus(temporalAmount), date.getClass()));
+    }
+    
+    @Override
+    public boolean isComparableTo(FHIRPathNode other) {
+        return other instanceof FHIRPathDateValue || 
+                other.getValue() instanceof FHIRPathDateValue;
+    }
+
+    @Override
+    public int compareTo(FHIRPathNode other) {
+        if (!isComparableTo(other)) {
+            throw new IllegalArgumentException();
+        }
+        if (other instanceof FHIRPathDateValue) {
+            return compareTo((FHIRPathDateValue) other);
+        }
+        return compareTo((FHIRPathDateValue) other.getValue());
+    }
+
+    private int compareTo(FHIRPathDateValue value) {
+        if (date instanceof Year || value.date instanceof Year) {
+            return Year.from(date).compareTo(Year.from(value.date));
+        }
+        if (date instanceof YearMonth || value.date instanceof YearMonth) {
+            return YearMonth.from(date).compareTo(YearMonth.from(value.date));
+        }
+        return LocalDate.from(date).compareTo(LocalDate.from(value.date));
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (!(obj instanceof FHIRPathNode)) {
+            return false;
+        }
+        FHIRPathNode other = (FHIRPathNode) obj;
+        if (other instanceof FHIRPathDateValue) {
+            return Objects.equals(date, ((FHIRPathDateValue) other).date());
+        }
+        if (other.getValue() instanceof FHIRPathElementNode) {
+            return Objects.equals(date, ((FHIRPathDateValue) other.getValue()).date());
+        }
+        return false;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hashCode(date);
+    }
+
+    @Override
+    public String toString() {
+        return DATE_PARSER_FORMATTER.format(date);
+    }
+    
+    public static void main(String[] args) {
+        System.out.println(LocalDate.from(Year.now()));
+    }
+
+    @Override
+    public void accept(FHIRPathNodeVisitor visitor) {
+        visitor.visit(this);
+    }
+}
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathDecimalValue.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathDecimalValue.java
index f48487bbe73..15f3cf952fb 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathDecimalValue.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathDecimalValue.java
@@ -71,7 +71,7 @@ public Builder path(String path) {
         }
         
         @Override
-        public Builder value(FHIRPathPrimitiveValue value) {
+        public Builder value(FHIRPathSystemValue value) {
             return this;
         }
         
@@ -163,7 +163,7 @@ public String toString() {
     }
 
     @Override
-    public <T> void accept(T param, FHIRPathNodeVisitor<T> visitor) {
-        visitor.visit(param, this);
+    public void accept(FHIRPathNodeVisitor visitor) {
+        visitor.visit(this);
     }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathElementNode.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathElementNode.java
index d76844b2a7e..be824237b2d 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathElementNode.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathElementNode.java
@@ -75,7 +75,7 @@ public Builder path(String path) {
             return (Builder) super.path(path);
         }
         
-        public Builder value(FHIRPathPrimitiveValue value) {
+        public Builder value(FHIRPathSystemValue value) {
             return (Builder) super.value(value);
         }
         
@@ -96,7 +96,7 @@ public FHIRPathElementNode build() {
     @Override
     public boolean isComparableTo(FHIRPathNode other) {
         if (hasValue()) {
-            if (other instanceof FHIRPathPrimitiveValue) {
+            if (other instanceof FHIRPathSystemValue) {
                 return getValue().isComparableTo(other);
             }
             if (other.hasValue()) {
@@ -111,7 +111,7 @@ public int compareTo(FHIRPathNode other) {
         if (!isComparableTo(other)) {
             throw new IllegalArgumentException();
         }
-        if (other instanceof FHIRPathPrimitiveValue) {
+        if (other instanceof FHIRPathSystemValue) {
             return getValue().compareTo(other);
         }
         return getValue().compareTo(other.getValue());
@@ -130,8 +130,8 @@ public boolean equals(Object obj) {
         }
         FHIRPathNode other = (FHIRPathNode) obj;
         if (hasValue()) {
-            if (other instanceof FHIRPathPrimitiveValue) {
-                return getValue().equals((FHIRPathPrimitiveValue) other);
+            if (other instanceof FHIRPathSystemValue) {
+                return getValue().equals((FHIRPathSystemValue) other);
             }
             if (other.hasValue()) {
                 return getValue().equals(other.getValue());
@@ -148,6 +148,7 @@ public int hashCode() {
         return Objects.hashCode(element);
     }
     
+    @Override
     public String toString() {
         if (hasValue()) {
             return "FHIRPathElementNode: [type: " + type() + ", value: " + value.toString() + "]";
@@ -156,7 +157,7 @@ public String toString() {
     }
 
     @Override
-    public <T> void accept(T param, FHIRPathNodeVisitor<T> visitor) {
-        visitor.visit(param, this);
+    public void accept(FHIRPathNodeVisitor visitor) {
+        visitor.visit(this);
     }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathIntegerValue.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathIntegerValue.java
index 8012892a990..811eb178144 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathIntegerValue.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathIntegerValue.java
@@ -72,7 +72,7 @@ public Builder path(String path) {
         }
         
         @Override
-        public Builder value(FHIRPathPrimitiveValue value) {
+        public Builder value(FHIRPathSystemValue value) {
             return this;
         }
         
@@ -182,7 +182,7 @@ public String toString() {
     }
 
     @Override
-    public <T> void accept(T param, FHIRPathNodeVisitor<T> visitor) {
-        visitor.visit(param, this);
+    public void accept(FHIRPathNodeVisitor visitor) {
+        visitor.visit(this);
     }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathLexer.interp b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathLexer.interp
new file mode 100644
index 00000000000..f757765fd57
--- /dev/null
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathLexer.interp
@@ -0,0 +1,215 @@
+token literal names:
+null
+'.'
+'['
+']'
+'+'
+'-'
+'*'
+'/'
+'div'
+'mod'
+'&'
+'is'
+'as'
+'|'
+'<='
+'<'
+'>'
+'>='
+'='
+'~'
+'!='
+'!~'
+'in'
+'contains'
+'and'
+'or'
+'xor'
+'implies'
+'('
+')'
+'{'
+'}'
+'true'
+'false'
+'%'
+'$this'
+'$index'
+'$total'
+','
+'year'
+'month'
+'week'
+'day'
+'hour'
+'minute'
+'second'
+'millisecond'
+'years'
+'months'
+'weeks'
+'days'
+'hours'
+'minutes'
+'seconds'
+'milliseconds'
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+
+token symbolic names:
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+null
+DATE
+DATETIME
+TIME
+IDENTIFIER
+DELIMITEDIDENTIFIER
+STRING
+NUMBER
+WS
+COMMENT
+LINE_COMMENT
+
+rule names:
+T__0
+T__1
+T__2
+T__3
+T__4
+T__5
+T__6
+T__7
+T__8
+T__9
+T__10
+T__11
+T__12
+T__13
+T__14
+T__15
+T__16
+T__17
+T__18
+T__19
+T__20
+T__21
+T__22
+T__23
+T__24
+T__25
+T__26
+T__27
+T__28
+T__29
+T__30
+T__31
+T__32
+T__33
+T__34
+T__35
+T__36
+T__37
+T__38
+T__39
+T__40
+T__41
+T__42
+T__43
+T__44
+T__45
+T__46
+T__47
+T__48
+T__49
+T__50
+T__51
+T__52
+T__53
+DATE
+DATETIME
+TIME
+DATEFORMAT
+TIMEFORMAT
+TIMEZONEOFFSETFORMAT
+IDENTIFIER
+DELIMITEDIDENTIFIER
+STRING
+NUMBER
+WS
+COMMENT
+LINE_COMMENT
+ESC
+UNICODE
+HEX
+
+channel names:
+DEFAULT_TOKEN_CHANNEL
+HIDDEN
+
+mode names:
+DEFAULT_MODE
+
+atn:
+[3, 24715, 42794, 33075, 47597, 16764, 15335, 30598, 22884, 2, 66, 525, 8, 1, 4, 2, 9, 2, 4, 3, 9, 3, 4, 4, 9, 4, 4, 5, 9, 5, 4, 6, 9, 6, 4, 7, 9, 7, 4, 8, 9, 8, 4, 9, 9, 9, 4, 10, 9, 10, 4, 11, 9, 11, 4, 12, 9, 12, 4, 13, 9, 13, 4, 14, 9, 14, 4, 15, 9, 15, 4, 16, 9, 16, 4, 17, 9, 17, 4, 18, 9, 18, 4, 19, 9, 19, 4, 20, 9, 20, 4, 21, 9, 21, 4, 22, 9, 22, 4, 23, 9, 23, 4, 24, 9, 24, 4, 25, 9, 25, 4, 26, 9, 26, 4, 27, 9, 27, 4, 28, 9, 28, 4, 29, 9, 29, 4, 30, 9, 30, 4, 31, 9, 31, 4, 32, 9, 32, 4, 33, 9, 33, 4, 34, 9, 34, 4, 35, 9, 35, 4, 36, 9, 36, 4, 37, 9, 37, 4, 38, 9, 38, 4, 39, 9, 39, 4, 40, 9, 40, 4, 41, 9, 41, 4, 42, 9, 42, 4, 43, 9, 43, 4, 44, 9, 44, 4, 45, 9, 45, 4, 46, 9, 46, 4, 47, 9, 47, 4, 48, 9, 48, 4, 49, 9, 49, 4, 50, 9, 50, 4, 51, 9, 51, 4, 52, 9, 52, 4, 53, 9, 53, 4, 54, 9, 54, 4, 55, 9, 55, 4, 56, 9, 56, 4, 57, 9, 57, 4, 58, 9, 58, 4, 59, 9, 59, 4, 60, 9, 60, 4, 61, 9, 61, 4, 62, 9, 62, 4, 63, 9, 63, 4, 64, 9, 64, 4, 65, 9, 65, 4, 66, 9, 66, 4, 67, 9, 67, 4, 68, 9, 68, 4, 69, 9, 69, 4, 70, 9, 70, 4, 71, 9, 71, 3, 2, 3, 2, 3, 3, 3, 3, 3, 4, 3, 4, 3, 5, 3, 5, 3, 6, 3, 6, 3, 7, 3, 7, 3, 8, 3, 8, 3, 9, 3, 9, 3, 9, 3, 9, 3, 10, 3, 10, 3, 10, 3, 10, 3, 11, 3, 11, 3, 12, 3, 12, 3, 12, 3, 13, 3, 13, 3, 13, 3, 14, 3, 14, 3, 15, 3, 15, 3, 15, 3, 16, 3, 16, 3, 17, 3, 17, 3, 18, 3, 18, 3, 18, 3, 19, 3, 19, 3, 20, 3, 20, 3, 21, 3, 21, 3, 21, 3, 22, 3, 22, 3, 22, 3, 23, 3, 23, 3, 23, 3, 24, 3, 24, 3, 24, 3, 24, 3, 24, 3, 24, 3, 24, 3, 24, 3, 24, 3, 25, 3, 25, 3, 25, 3, 25, 3, 26, 3, 26, 3, 26, 3, 27, 3, 27, 3, 27, 3, 27, 3, 28, 3, 28, 3, 28, 3, 28, 3, 28, 3, 28, 3, 28, 3, 28, 3, 29, 3, 29, 3, 30, 3, 30, 3, 31, 3, 31, 3, 32, 3, 32, 3, 33, 3, 33, 3, 33, 3, 33, 3, 33, 3, 34, 3, 34, 3, 34, 3, 34, 3, 34, 3, 34, 3, 35, 3, 35, 3, 36, 3, 36, 3, 36, 3, 36, 3, 36, 3, 36, 3, 37, 3, 37, 3, 37, 3, 37, 3, 37, 3, 37, 3, 37, 3, 38, 3, 38, 3, 38, 3, 38, 3, 38, 3, 38, 3, 38, 3, 39, 3, 39, 3, 40, 3, 40, 3, 40, 3, 40, 3, 40, 3, 41, 3, 41, 3, 41, 3, 41, 3, 41, 3, 41, 3, 42, 3, 42, 3, 42, 3, 42, 3, 42, 3, 43, 3, 43, 3, 43, 3, 43, 3, 44, 3, 44, 3, 44, 3, 44, 3, 44, 3, 45, 3, 45, 3, 45, 3, 45, 3, 45, 3, 45, 3, 45, 3, 46, 3, 46, 3, 46, 3, 46, 3, 46, 3, 46, 3, 46, 3, 47, 3, 47, 3, 47, 3, 47, 3, 47, 3, 47, 3, 47, 3, 47, 3, 47, 3, 47, 3, 47, 3, 47, 3, 48, 3, 48, 3, 48, 3, 48, 3, 48, 3, 48, 3, 49, 3, 49, 3, 49, 3, 49, 3, 49, 3, 49, 3, 49, 3, 50, 3, 50, 3, 50, 3, 50, 3, 50, 3, 50, 3, 51, 3, 51, 3, 51, 3, 51, 3, 51, 3, 52, 3, 52, 3, 52, 3, 52, 3, 52, 3, 52, 3, 53, 3, 53, 3, 53, 3, 53, 3, 53, 3, 53, 3, 53, 3, 53, 3, 54, 3, 54, 3, 54, 3, 54, 3, 54, 3, 54, 3, 54, 3, 54, 3, 55, 3, 55, 3, 55, 3, 55, 3, 55, 3, 55, 3, 55, 3, 55, 3, 55, 3, 55, 3, 55, 3, 55, 3, 55, 3, 56, 3, 56, 3, 56, 3, 57, 3, 57, 3, 57, 3, 57, 3, 57, 5, 57, 388, 10, 57, 5, 57, 390, 10, 57, 3, 58, 3, 58, 3, 58, 3, 58, 3, 59, 3, 59, 3, 59, 3, 59, 3, 59, 3, 59, 3, 59, 3, 59, 3, 59, 3, 59, 5, 59, 406, 10, 59, 5, 59, 408, 10, 59, 3, 60, 3, 60, 3, 60, 3, 60, 3, 60, 3, 60, 3, 60, 3, 60, 3, 60, 3, 60, 6, 60, 420, 10, 60, 13, 60, 14, 60, 421, 5, 60, 424, 10, 60, 5, 60, 426, 10, 60, 5, 60, 428, 10, 60, 3, 61, 3, 61, 3, 61, 3, 61, 3, 61, 3, 61, 3, 61, 5, 61, 437, 10, 61, 3, 62, 5, 62, 440, 10, 62, 3, 62, 7, 62, 443, 10, 62, 12, 62, 14, 62, 446, 11, 62, 3, 63, 3, 63, 3, 63, 7, 63, 451, 10, 63, 12, 63, 14, 63, 454, 11, 63, 3, 63, 3, 63, 3, 64, 3, 64, 3, 64, 7, 64, 461, 10, 64, 12, 64, 14, 64, 464, 11, 64, 3, 64, 3, 64, 3, 65, 6, 65, 469, 10, 65, 13, 65, 14, 65, 470, 3, 65, 3, 65, 6, 65, 475, 10, 65, 13, 65, 14, 65, 476, 5, 65, 479, 10, 65, 3, 66, 6, 66, 482, 10, 66, 13, 66, 14, 66, 483, 3, 66, 3, 66, 3, 67, 3, 67, 3, 67, 3, 67, 7, 67, 492, 10, 67, 12, 67, 14, 67, 495, 11, 67, 3, 67, 3, 67, 3, 67, 3, 67, 3, 67, 3, 68, 3, 68, 3, 68, 3, 68, 7, 68, 506, 10, 68, 12, 68, 14, 68, 509, 11, 68, 3, 68, 3, 68, 3, 69, 3, 69, 3, 69, 5, 69, 516, 10, 69, 3, 70, 3, 70, 3, 70, 3, 70, 3, 70, 3, 70, 3, 71, 3, 71, 5, 452, 462, 493, 2, 72, 3, 3, 5, 4, 7, 5, 9, 6, 11, 7, 13, 8, 15, 9, 17, 10, 19, 11, 21, 12, 23, 13, 25, 14, 27, 15, 29, 16, 31, 17, 33, 18, 35, 19, 37, 20, 39, 21, 41, 22, 43, 23, 45, 24, 47, 25, 49, 26, 51, 27, 53, 28, 55, 29, 57, 30, 59, 31, 61, 32, 63, 33, 65, 34, 67, 35, 69, 36, 71, 37, 73, 38, 75, 39, 77, 40, 79, 41, 81, 42, 83, 43, 85, 44, 87, 45, 89, 46, 91, 47, 93, 48, 95, 49, 97, 50, 99, 51, 101, 52, 103, 53, 105, 54, 107, 55, 109, 56, 111, 57, 113, 58, 115, 59, 117, 2, 119, 2, 121, 2, 123, 60, 125, 61, 127, 62, 129, 63, 131, 64, 133, 65, 135, 66, 137, 2, 139, 2, 141, 2, 3, 2, 10, 3, 2, 50, 59, 4, 2, 45, 45, 47, 47, 5, 2, 67, 92, 97, 97, 99, 124, 6, 2, 50, 59, 67, 92, 97, 97, 99, 124, 5, 2, 11, 12, 15, 15, 34, 34, 4, 2, 12, 12, 15, 15, 10, 2, 41, 41, 49, 49, 94, 94, 98, 98, 104, 104, 112, 112, 116, 116, 118, 118, 5, 2, 50, 59, 67, 72, 99, 104, 2, 539, 2, 3, 3, 2, 2, 2, 2, 5, 3, 2, 2, 2, 2, 7, 3, 2, 2, 2, 2, 9, 3, 2, 2, 2, 2, 11, 3, 2, 2, 2, 2, 13, 3, 2, 2, 2, 2, 15, 3, 2, 2, 2, 2, 17, 3, 2, 2, 2, 2, 19, 3, 2, 2, 2, 2, 21, 3, 2, 2, 2, 2, 23, 3, 2, 2, 2, 2, 25, 3, 2, 2, 2, 2, 27, 3, 2, 2, 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2, 2, 5, 145, 3, 2, 2, 2, 7, 147, 3, 2, 2, 2, 9, 149, 3, 2, 2, 2, 11, 151, 3, 2, 2, 2, 13, 153, 3, 2, 2, 2, 15, 155, 3, 2, 2, 2, 17, 157, 3, 2, 2, 2, 19, 161, 3, 2, 2, 2, 21, 165, 3, 2, 2, 2, 23, 167, 3, 2, 2, 2, 25, 170, 3, 2, 2, 2, 27, 173, 3, 2, 2, 2, 29, 175, 3, 2, 2, 2, 31, 178, 3, 2, 2, 2, 33, 180, 3, 2, 2, 2, 35, 182, 3, 2, 2, 2, 37, 185, 3, 2, 2, 2, 39, 187, 3, 2, 2, 2, 41, 189, 3, 2, 2, 2, 43, 192, 3, 2, 2, 2, 45, 195, 3, 2, 2, 2, 47, 198, 3, 2, 2, 2, 49, 207, 3, 2, 2, 2, 51, 211, 3, 2, 2, 2, 53, 214, 3, 2, 2, 2, 55, 218, 3, 2, 2, 2, 57, 226, 3, 2, 2, 2, 59, 228, 3, 2, 2, 2, 61, 230, 3, 2, 2, 2, 63, 232, 3, 2, 2, 2, 65, 234, 3, 2, 2, 2, 67, 239, 3, 2, 2, 2, 69, 245, 3, 2, 2, 2, 71, 247, 3, 2, 2, 2, 73, 253, 3, 2, 2, 2, 75, 260, 3, 2, 2, 2, 77, 267, 3, 2, 2, 2, 79, 269, 3, 2, 2, 2, 81, 274, 3, 2, 2, 2, 83, 280, 3, 2, 2, 2, 85, 285, 3, 2, 2, 2, 87, 289, 3, 2, 2, 2, 89, 294, 3, 2, 2, 2, 91, 301, 3, 2, 2, 2, 93, 308, 3, 2, 2, 2, 95, 320, 3, 2, 2, 2, 97, 326, 3, 2, 2, 2, 99, 333, 3, 2, 2, 2, 101, 339, 3, 2, 2, 2, 103, 344, 3, 2, 2, 2, 105, 350, 3, 2, 2, 2, 107, 358, 3, 2, 2, 2, 109, 366, 3, 2, 2, 2, 111, 379, 3, 2, 2, 2, 113, 382, 3, 2, 2, 2, 115, 391, 3, 2, 2, 2, 117, 395, 3, 2, 2, 2, 119, 409, 3, 2, 2, 2, 121, 436, 3, 2, 2, 2, 123, 439, 3, 2, 2, 2, 125, 447, 3, 2, 2, 2, 127, 457, 3, 2, 2, 2, 129, 468, 3, 2, 2, 2, 131, 481, 3, 2, 2, 2, 133, 487, 3, 2, 2, 2, 135, 501, 3, 2, 2, 2, 137, 512, 3, 2, 2, 2, 139, 517, 3, 2, 2, 2, 141, 523, 3, 2, 2, 2, 143, 144, 7, 48, 2, 2, 144, 4, 3, 2, 2, 2, 145, 146, 7, 93, 2, 2, 146, 6, 3, 2, 2, 2, 147, 148, 7, 95, 2, 2, 148, 8, 3, 2, 2, 2, 149, 150, 7, 45, 2, 2, 150, 10, 3, 2, 2, 2, 151, 152, 7, 47, 2, 2, 152, 12, 3, 2, 2, 2, 153, 154, 7, 44, 2, 2, 154, 14, 3, 2, 2, 2, 155, 156, 7, 49, 2, 2, 156, 16, 3, 2, 2, 2, 157, 158, 7, 102, 2, 2, 158, 159, 7, 107, 2, 2, 159, 160, 7, 120, 2, 2, 160, 18, 3, 2, 2, 2, 161, 162, 7, 111, 2, 2, 162, 163, 7, 113, 2, 2, 163, 164, 7, 102, 2, 2, 164, 20, 3, 2, 2, 2, 165, 166, 7, 40, 2, 2, 166, 22, 3, 2, 2, 2, 167, 168, 7, 107, 2, 2, 168, 169, 7, 117, 2, 2, 169, 24, 3, 2, 2, 2, 170, 171, 7, 99, 2, 2, 171, 172, 7, 117, 2, 2, 172, 26, 3, 2, 2, 2, 173, 174, 7, 126, 2, 2, 174, 28, 3, 2, 2, 2, 175, 176, 7, 62, 2, 2, 176, 177, 7, 63, 2, 2, 177, 30, 3, 2, 2, 2, 178, 179, 7, 62, 2, 2, 179, 32, 3, 2, 2, 2, 180, 181, 7, 64, 2, 2, 181, 34, 3, 2, 2, 2, 182, 183, 7, 64, 2, 2, 183, 184, 7, 63, 2, 2, 184, 36, 3, 2, 2, 2, 185, 186, 7, 63, 2, 2, 186, 38, 3, 2, 2, 2, 187, 188, 7, 128, 2, 2, 188, 40, 3, 2, 2, 2, 189, 190, 7, 35, 2, 2, 190, 191, 7, 63, 2, 2, 191, 42, 3, 2, 2, 2, 192, 193, 7, 35, 2, 2, 193, 194, 7, 128, 2, 2, 194, 44, 3, 2, 2, 2, 195, 196, 7, 107, 2, 2, 196, 197, 7, 112, 2, 2, 197, 46, 3, 2, 2, 2, 198, 199, 7, 101, 2, 2, 199, 200, 7, 113, 2, 2, 200, 201, 7, 112, 2, 2, 201, 202, 7, 118, 2, 2, 202, 203, 7, 99, 2, 2, 203, 204, 7, 107, 2, 2, 204, 205, 7, 112, 2, 2, 205, 206, 7, 117, 2, 2, 206, 48, 3, 2, 2, 2, 207, 208, 7, 99, 2, 2, 208, 209, 7, 112, 2, 2, 209, 210, 7, 102, 2, 2, 210, 50, 3, 2, 2, 2, 211, 212, 7, 113, 2, 2, 212, 213, 7, 116, 2, 2, 213, 52, 3, 2, 2, 2, 214, 215, 7, 122, 2, 2, 215, 216, 7, 113, 2, 2, 216, 217, 7, 116, 2, 2, 217, 54, 3, 2, 2, 2, 218, 219, 7, 107, 2, 2, 219, 220, 7, 111, 2, 2, 220, 221, 7, 114, 2, 2, 221, 222, 7, 110, 2, 2, 222, 223, 7, 107, 2, 2, 223, 224, 7, 103, 2, 2, 224, 225, 7, 117, 2, 2, 225, 56, 3, 2, 2, 2, 226, 227, 7, 42, 2, 2, 227, 58, 3, 2, 2, 2, 228, 229, 7, 43, 2, 2, 229, 60, 3, 2, 2, 2, 230, 231, 7, 125, 2, 2, 231, 62, 3, 2, 2, 2, 232, 233, 7, 127, 2, 2, 233, 64, 3, 2, 2, 2, 234, 235, 7, 118, 2, 2, 235, 236, 7, 116, 2, 2, 236, 237, 7, 119, 2, 2, 237, 238, 7, 103, 2, 2, 238, 66, 3, 2, 2, 2, 239, 240, 7, 104, 2, 2, 240, 241, 7, 99, 2, 2, 241, 242, 7, 110, 2, 2, 242, 243, 7, 117, 2, 2, 243, 244, 7, 103, 2, 2, 244, 68, 3, 2, 2, 2, 245, 246, 7, 39, 2, 2, 246, 70, 3, 2, 2, 2, 247, 248, 7, 38, 2, 2, 248, 249, 7, 118, 2, 2, 249, 250, 7, 106, 2, 2, 250, 251, 7, 107, 2, 2, 251, 252, 7, 117, 2, 2, 252, 72, 3, 2, 2, 2, 253, 254, 7, 38, 2, 2, 254, 255, 7, 107, 2, 2, 255, 256, 7, 112, 2, 2, 256, 257, 7, 102, 2, 2, 257, 258, 7, 103, 2, 2, 258, 259, 7, 122, 2, 2, 259, 74, 3, 2, 2, 2, 260, 261, 7, 38, 2, 2, 261, 262, 7, 118, 2, 2, 262, 263, 7, 113, 2, 2, 263, 264, 7, 118, 2, 2, 264, 265, 7, 99, 2, 2, 265, 266, 7, 110, 2, 2, 266, 76, 3, 2, 2, 2, 267, 268, 7, 46, 2, 2, 268, 78, 3, 2, 2, 2, 269, 270, 7, 123, 2, 2, 270, 271, 7, 103, 2, 2, 271, 272, 7, 99, 2, 2, 272, 273, 7, 116, 2, 2, 273, 80, 3, 2, 2, 2, 274, 275, 7, 111, 2, 2, 275, 276, 7, 113, 2, 2, 276, 277, 7, 112, 2, 2, 277, 278, 7, 118, 2, 2, 278, 279, 7, 106, 2, 2, 279, 82, 3, 2, 2, 2, 280, 281, 7, 121, 2, 2, 281, 282, 7, 103, 2, 2, 282, 283, 7, 103, 2, 2, 283, 284, 7, 109, 2, 2, 284, 84, 3, 2, 2, 2, 285, 286, 7, 102, 2, 2, 286, 287, 7, 99, 2, 2, 287, 288, 7, 123, 2, 2, 288, 86, 3, 2, 2, 2, 289, 290, 7, 106, 2, 2, 290, 291, 7, 113, 2, 2, 291, 292, 7, 119, 2, 2, 292, 293, 7, 116, 2, 2, 293, 88, 3, 2, 2, 2, 294, 295, 7, 111, 2, 2, 295, 296, 7, 107, 2, 2, 296, 297, 7, 112, 2, 2, 297, 298, 7, 119, 2, 2, 298, 299, 7, 118, 2, 2, 299, 300, 7, 103, 2, 2, 300, 90, 3, 2, 2, 2, 301, 302, 7, 117, 2, 2, 302, 303, 7, 103, 2, 2, 303, 304, 7, 101, 2, 2, 304, 305, 7, 113, 2, 2, 305, 306, 7, 112, 2, 2, 306, 307, 7, 102, 2, 2, 307, 92, 3, 2, 2, 2, 308, 309, 7, 111, 2, 2, 309, 310, 7, 107, 2, 2, 310, 311, 7, 110, 2, 2, 311, 312, 7, 110, 2, 2, 312, 313, 7, 107, 2, 2, 313, 314, 7, 117, 2, 2, 314, 315, 7, 103, 2, 2, 315, 316, 7, 101, 2, 2, 316, 317, 7, 113, 2, 2, 317, 318, 7, 112, 2, 2, 318, 319, 7, 102, 2, 2, 319, 94, 3, 2, 2, 2, 320, 321, 7, 123, 2, 2, 321, 322, 7, 103, 2, 2, 322, 323, 7, 99, 2, 2, 323, 324, 7, 116, 2, 2, 324, 325, 7, 117, 2, 2, 325, 96, 3, 2, 2, 2, 326, 327, 7, 111, 2, 2, 327, 328, 7, 113, 2, 2, 328, 329, 7, 112, 2, 2, 329, 330, 7, 118, 2, 2, 330, 331, 7, 106, 2, 2, 331, 332, 7, 117, 2, 2, 332, 98, 3, 2, 2, 2, 333, 334, 7, 121, 2, 2, 334, 335, 7, 103, 2, 2, 335, 336, 7, 103, 2, 2, 336, 337, 7, 109, 2, 2, 337, 338, 7, 117, 2, 2, 338, 100, 3, 2, 2, 2, 339, 340, 7, 102, 2, 2, 340, 341, 7, 99, 2, 2, 341, 342, 7, 123, 2, 2, 342, 343, 7, 117, 2, 2, 343, 102, 3, 2, 2, 2, 344, 345, 7, 106, 2, 2, 345, 346, 7, 113, 2, 2, 346, 347, 7, 119, 2, 2, 347, 348, 7, 116, 2, 2, 348, 349, 7, 117, 2, 2, 349, 104, 3, 2, 2, 2, 350, 351, 7, 111, 2, 2, 351, 352, 7, 107, 2, 2, 352, 353, 7, 112, 2, 2, 353, 354, 7, 119, 2, 2, 354, 355, 7, 118, 2, 2, 355, 356, 7, 103, 2, 2, 356, 357, 7, 117, 2, 2, 357, 106, 3, 2, 2, 2, 358, 359, 7, 117, 2, 2, 359, 360, 7, 103, 2, 2, 360, 361, 7, 101, 2, 2, 361, 362, 7, 113, 2, 2, 362, 363, 7, 112, 2, 2, 363, 364, 7, 102, 2, 2, 364, 365, 7, 117, 2, 2, 365, 108, 3, 2, 2, 2, 366, 367, 7, 111, 2, 2, 367, 368, 7, 107, 2, 2, 368, 369, 7, 110, 2, 2, 369, 370, 7, 110, 2, 2, 370, 371, 7, 107, 2, 2, 371, 372, 7, 117, 2, 2, 372, 373, 7, 103, 2, 2, 373, 374, 7, 101, 2, 2, 374, 375, 7, 113, 2, 2, 375, 376, 7, 112, 2, 2, 376, 377, 7, 102, 2, 2, 377, 378, 7, 117, 2, 2, 378, 110, 3, 2, 2, 2, 379, 380, 7, 66, 2, 2, 380, 381, 5, 117, 59, 2, 381, 112, 3, 2, 2, 2, 382, 383, 7, 66, 2, 2, 383, 384, 5, 117, 59, 2, 384, 389, 7, 86, 2, 2, 385, 387, 5, 119, 60, 2, 386, 388, 5, 121, 61, 2, 387, 386, 3, 2, 2, 2, 387, 388, 3, 2, 2, 2, 388, 390, 3, 2, 2, 2, 389, 385, 3, 2, 2, 2, 389, 390, 3, 2, 2, 2, 390, 114, 3, 2, 2, 2, 391, 392, 7, 66, 2, 2, 392, 393, 7, 86, 2, 2, 393, 394, 5, 119, 60, 2, 394, 116, 3, 2, 2, 2, 395, 396, 9, 2, 2, 2, 396, 397, 9, 2, 2, 2, 397, 398, 9, 2, 2, 2, 398, 407, 9, 2, 2, 2, 399, 400, 7, 47, 2, 2, 400, 401, 9, 2, 2, 2, 401, 405, 9, 2, 2, 2, 402, 403, 7, 47, 2, 2, 403, 404, 9, 2, 2, 2, 404, 406, 9, 2, 2, 2, 405, 402, 3, 2, 2, 2, 405, 406, 3, 2, 2, 2, 406, 408, 3, 2, 2, 2, 407, 399, 3, 2, 2, 2, 407, 408, 3, 2, 2, 2, 408, 118, 3, 2, 2, 2, 409, 410, 9, 2, 2, 2, 410, 427, 9, 2, 2, 2, 411, 412, 7, 60, 2, 2, 412, 413, 9, 2, 2, 2, 413, 425, 9, 2, 2, 2, 414, 415, 7, 60, 2, 2, 415, 416, 9, 2, 2, 2, 416, 423, 9, 2, 2, 2, 417, 419, 7, 48, 2, 2, 418, 420, 9, 2, 2, 2, 419, 418, 3, 2, 2, 2, 420, 421, 3, 2, 2, 2, 421, 419, 3, 2, 2, 2, 421, 422, 3, 2, 2, 2, 422, 424, 3, 2, 2, 2, 423, 417, 3, 2, 2, 2, 423, 424, 3, 2, 2, 2, 424, 426, 3, 2, 2, 2, 425, 414, 3, 2, 2, 2, 425, 426, 3, 2, 2, 2, 426, 428, 3, 2, 2, 2, 427, 411, 3, 2, 2, 2, 427, 428, 3, 2, 2, 2, 428, 120, 3, 2, 2, 2, 429, 437, 7, 92, 2, 2, 430, 431, 9, 3, 2, 2, 431, 432, 9, 2, 2, 2, 432, 433, 9, 2, 2, 2, 433, 434, 7, 60, 2, 2, 434, 435, 9, 2, 2, 2, 435, 437, 9, 2, 2, 2, 436, 429, 3, 2, 2, 2, 436, 430, 3, 2, 2, 2, 437, 122, 3, 2, 2, 2, 438, 440, 9, 4, 2, 2, 439, 438, 3, 2, 2, 2, 440, 444, 3, 2, 2, 2, 441, 443, 9, 5, 2, 2, 442, 441, 3, 2, 2, 2, 443, 446, 3, 2, 2, 2, 444, 442, 3, 2, 2, 2, 444, 445, 3, 2, 2, 2, 445, 124, 3, 2, 2, 2, 446, 444, 3, 2, 2, 2, 447, 452, 7, 98, 2, 2, 448, 451, 5, 137, 69, 2, 449, 451, 11, 2, 2, 2, 450, 448, 3, 2, 2, 2, 450, 449, 3, 2, 2, 2, 451, 454, 3, 2, 2, 2, 452, 453, 3, 2, 2, 2, 452, 450, 3, 2, 2, 2, 453, 455, 3, 2, 2, 2, 454, 452, 3, 2, 2, 2, 455, 456, 7, 98, 2, 2, 456, 126, 3, 2, 2, 2, 457, 462, 7, 41, 2, 2, 458, 461, 5, 137, 69, 2, 459, 461, 11, 2, 2, 2, 460, 458, 3, 2, 2, 2, 460, 459, 3, 2, 2, 2, 461, 464, 3, 2, 2, 2, 462, 463, 3, 2, 2, 2, 462, 460, 3, 2, 2, 2, 463, 465, 3, 2, 2, 2, 464, 462, 3, 2, 2, 2, 465, 466, 7, 41, 2, 2, 466, 128, 3, 2, 2, 2, 467, 469, 9, 2, 2, 2, 468, 467, 3, 2, 2, 2, 469, 470, 3, 2, 2, 2, 470, 468, 3, 2, 2, 2, 470, 471, 3, 2, 2, 2, 471, 478, 3, 2, 2, 2, 472, 474, 7, 48, 2, 2, 473, 475, 9, 2, 2, 2, 474, 473, 3, 2, 2, 2, 475, 476, 3, 2, 2, 2, 476, 474, 3, 2, 2, 2, 476, 477, 3, 2, 2, 2, 477, 479, 3, 2, 2, 2, 478, 472, 3, 2, 2, 2, 478, 479, 3, 2, 2, 2, 479, 130, 3, 2, 2, 2, 480, 482, 9, 6, 2, 2, 481, 480, 3, 2, 2, 2, 482, 483, 3, 2, 2, 2, 483, 481, 3, 2, 2, 2, 483, 484, 3, 2, 2, 2, 484, 485, 3, 2, 2, 2, 485, 486, 8, 66, 2, 2, 486, 132, 3, 2, 2, 2, 487, 488, 7, 49, 2, 2, 488, 489, 7, 44, 2, 2, 489, 493, 3, 2, 2, 2, 490, 492, 11, 2, 2, 2, 491, 490, 3, 2, 2, 2, 492, 495, 3, 2, 2, 2, 493, 494, 3, 2, 2, 2, 493, 491, 3, 2, 2, 2, 494, 496, 3, 2, 2, 2, 495, 493, 3, 2, 2, 2, 496, 497, 7, 44, 2, 2, 497, 498, 7, 49, 2, 2, 498, 499, 3, 2, 2, 2, 499, 500, 8, 67, 2, 2, 500, 134, 3, 2, 2, 2, 501, 502, 7, 49, 2, 2, 502, 503, 7, 49, 2, 2, 503, 507, 3, 2, 2, 2, 504, 506, 10, 7, 2, 2, 505, 504, 3, 2, 2, 2, 506, 509, 3, 2, 2, 2, 507, 505, 3, 2, 2, 2, 507, 508, 3, 2, 2, 2, 508, 510, 3, 2, 2, 2, 509, 507, 3, 2, 2, 2, 510, 511, 8, 68, 2, 2, 511, 136, 3, 2, 2, 2, 512, 515, 7, 94, 2, 2, 513, 516, 9, 8, 2, 2, 514, 516, 5, 139, 70, 2, 515, 513, 3, 2, 2, 2, 515, 514, 3, 2, 2, 2, 516, 138, 3, 2, 2, 2, 517, 518, 7, 119, 2, 2, 518, 519, 5, 141, 71, 2, 519, 520, 5, 141, 71, 2, 520, 521, 5, 141, 71, 2, 521, 522, 5, 141, 71, 2, 522, 140, 3, 2, 2, 2, 523, 524, 9, 9, 2, 2, 524, 142, 3, 2, 2, 2, 26, 2, 387, 389, 405, 407, 421, 423, 425, 427, 436, 439, 442, 444, 450, 452, 460, 462, 470, 476, 478, 483, 493, 507, 515, 3, 2, 3, 2]
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathLexer.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathLexer.java
index 79f80ddf54d..d9226a9123a 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathLexer.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathLexer.java
@@ -1,52 +1,79 @@
-/*
- * (C) Copyright IBM Corp. 2019
- *
- * SPDX-License-Identifier: Apache-2.0
- */
-
+// Generated from FHIRPath.g4 by ANTLR 4.7.2
 package com.ibm.fhir.model.path;
-
-import org.antlr.v4.runtime.CharStream;
 import org.antlr.v4.runtime.Lexer;
-import org.antlr.v4.runtime.RuntimeMetaData;
-import org.antlr.v4.runtime.Vocabulary;
-import org.antlr.v4.runtime.VocabularyImpl;
-import org.antlr.v4.runtime.atn.ATN;
-import org.antlr.v4.runtime.atn.ATNDeserializer;
-import org.antlr.v4.runtime.atn.LexerATNSimulator;
-import org.antlr.v4.runtime.atn.PredictionContextCache;
+import org.antlr.v4.runtime.CharStream;
+import org.antlr.v4.runtime.Token;
+import org.antlr.v4.runtime.TokenStream;
+import org.antlr.v4.runtime.*;
+import org.antlr.v4.runtime.atn.*;
 import org.antlr.v4.runtime.dfa.DFA;
+import org.antlr.v4.runtime.misc.*;
 
-@SuppressWarnings({ "all", "warnings", "unchecked", "unused", "cast" })
+@SuppressWarnings({"all", "warnings", "unchecked", "unused", "cast"})
 public class FHIRPathLexer extends Lexer {
-    static {
-        RuntimeMetaData.checkVersion("4.5.3", RuntimeMetaData.VERSION);
-    }
+    static { RuntimeMetaData.checkVersion("4.7.2", RuntimeMetaData.VERSION); }
 
     protected static final DFA[] _decisionToDFA;
-    protected static final PredictionContextCache _sharedContextCache = new PredictionContextCache();
-    public static final int T__0 = 1, T__1 = 2, T__2 = 3, T__3 = 4, T__4 = 5, T__5 = 6, T__6 = 7, T__7 = 8, T__8 = 9, T__9 = 10, T__10 = 11, T__11 = 12,
-            T__12 = 13, T__13 = 14, T__14 = 15, T__15 = 16, T__16 = 17, T__17 = 18, T__18 = 19, T__19 = 20, T__20 = 21, T__21 = 22, T__22 = 23, T__23 = 24,
-            T__24 = 25, T__25 = 26, T__26 = 27, T__27 = 28, T__28 = 29, T__29 = 30, T__30 = 31, T__31 = 32, T__32 = 33, T__33 = 34, T__34 = 35, T__35 = 36,
-            T__36 = 37, T__37 = 38, T__38 = 39, T__39 = 40, T__40 = 41, T__41 = 42, T__42 = 43, T__43 = 44, T__44 = 45, T__45 = 46, T__46 = 47, T__47 = 48,
-            T__48 = 49, T__49 = 50, T__50 = 51, T__51 = 52, T__52 = 53, T__53 = 54, DATETIME = 55, TIME = 56, IDENTIFIER = 57, DELIMITEDIDENTIFIER = 58,
-            STRING = 59, NUMBER = 60, WS = 61, COMMENT = 62, LINE_COMMENT = 63;
-    public static String[] modeNames = { "DEFAULT_MODE" };
+    protected static final PredictionContextCache _sharedContextCache =
+        new PredictionContextCache();
+    public static final int
+        T__0=1, T__1=2, T__2=3, T__3=4, T__4=5, T__5=6, T__6=7, T__7=8, T__8=9, 
+        T__9=10, T__10=11, T__11=12, T__12=13, T__13=14, T__14=15, T__15=16, T__16=17, 
+        T__17=18, T__18=19, T__19=20, T__20=21, T__21=22, T__22=23, T__23=24, 
+        T__24=25, T__25=26, T__26=27, T__27=28, T__28=29, T__29=30, T__30=31, 
+        T__31=32, T__32=33, T__33=34, T__34=35, T__35=36, T__36=37, T__37=38, 
+        T__38=39, T__39=40, T__40=41, T__41=42, T__42=43, T__43=44, T__44=45, 
+        T__45=46, T__46=47, T__47=48, T__48=49, T__49=50, T__50=51, T__51=52, 
+        T__52=53, T__53=54, DATE=55, DATETIME=56, TIME=57, IDENTIFIER=58, DELIMITEDIDENTIFIER=59, 
+        STRING=60, NUMBER=61, WS=62, COMMENT=63, LINE_COMMENT=64;
+    public static String[] channelNames = {
+        "DEFAULT_TOKEN_CHANNEL", "HIDDEN"
+    };
+
+    public static String[] modeNames = {
+        "DEFAULT_MODE"
+    };
 
-    public static final String[] ruleNames = { "T__0", "T__1", "T__2", "T__3", "T__4", "T__5", "T__6", "T__7", "T__8", "T__9", "T__10", "T__11", "T__12",
-            "T__13", "T__14", "T__15", "T__16", "T__17", "T__18", "T__19", "T__20", "T__21", "T__22", "T__23", "T__24", "T__25", "T__26", "T__27", "T__28",
-            "T__29", "T__30", "T__31", "T__32", "T__33", "T__34", "T__35", "T__36", "T__37", "T__38", "T__39", "T__40", "T__41", "T__42", "T__43", "T__44",
-            "T__45", "T__46", "T__47", "T__48", "T__49", "T__50", "T__51", "T__52", "T__53", "DATETIME", "TIME", "TIMEFORMAT", "IDENTIFIER",
-            "DELIMITEDIDENTIFIER", "STRING", "NUMBER", "WS", "COMMENT", "LINE_COMMENT", "ESC", "UNICODE", "HEX" };
+    private static String[] makeRuleNames() {
+        return new String[] {
+            "T__0", "T__1", "T__2", "T__3", "T__4", "T__5", "T__6", "T__7", "T__8", 
+            "T__9", "T__10", "T__11", "T__12", "T__13", "T__14", "T__15", "T__16", 
+            "T__17", "T__18", "T__19", "T__20", "T__21", "T__22", "T__23", "T__24", 
+            "T__25", "T__26", "T__27", "T__28", "T__29", "T__30", "T__31", "T__32", 
+            "T__33", "T__34", "T__35", "T__36", "T__37", "T__38", "T__39", "T__40", 
+            "T__41", "T__42", "T__43", "T__44", "T__45", "T__46", "T__47", "T__48", 
+            "T__49", "T__50", "T__51", "T__52", "T__53", "DATE", "DATETIME", "TIME", 
+            "DATEFORMAT", "TIMEFORMAT", "TIMEZONEOFFSETFORMAT", "IDENTIFIER", "DELIMITEDIDENTIFIER", 
+            "STRING", "NUMBER", "WS", "COMMENT", "LINE_COMMENT", "ESC", "UNICODE", 
+            "HEX"
+        };
+    }
+    public static final String[] ruleNames = makeRuleNames();
 
-    private static final String[] _LITERAL_NAMES = { null, "'.'", "'['", "']'", "'+'", "'-'", "'*'", "'/'", "'div'", "'mod'", "'&'", "'is'", "'as'", "'|'",
-            "'<='", "'<'", "'>'", "'>='", "'='", "'~'", "'!='", "'!~'", "'in'", "'contains'", "'and'", "'or'", "'xor'", "'implies'", "'('", "')'", "'{'", "'}'",
-            "'true'", "'false'", "'%'", "'$this'", "'$index'", "'$total'", "','", "'year'", "'month'", "'week'", "'day'", "'hour'", "'minute'", "'second'",
-            "'millisecond'", "'years'", "'months'", "'weeks'", "'days'", "'hours'", "'minutes'", "'seconds'", "'milliseconds'" };
-    private static final String[] _SYMBOLIC_NAMES = { null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null,
-            null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null,
-            null, null, null, null, null, null, null, null, null, null, null, null, null, null, "DATETIME", "TIME", "IDENTIFIER", "DELIMITEDIDENTIFIER",
-            "STRING", "NUMBER", "WS", "COMMENT", "LINE_COMMENT" };
+    private static String[] makeLiteralNames() {
+        return new String[] {
+            null, "'.'", "'['", "']'", "'+'", "'-'", "'*'", "'/'", "'div'", "'mod'", 
+            "'&'", "'is'", "'as'", "'|'", "'<='", "'<'", "'>'", "'>='", "'='", "'~'", 
+            "'!='", "'!~'", "'in'", "'contains'", "'and'", "'or'", "'xor'", "'implies'", 
+            "'('", "')'", "'{'", "'}'", "'true'", "'false'", "'%'", "'$this'", "'$index'", 
+            "'$total'", "','", "'year'", "'month'", "'week'", "'day'", "'hour'", 
+            "'minute'", "'second'", "'millisecond'", "'years'", "'months'", "'weeks'", 
+            "'days'", "'hours'", "'minutes'", "'seconds'", "'milliseconds'"
+        };
+    }
+    private static final String[] _LITERAL_NAMES = makeLiteralNames();
+    private static String[] makeSymbolicNames() {
+        return new String[] {
+            null, null, null, null, null, null, null, null, null, null, null, null, 
+            null, null, null, null, null, null, null, null, null, null, null, null, 
+            null, null, null, null, null, null, null, null, null, null, null, null, 
+            null, null, null, null, null, null, null, null, null, null, null, null, 
+            null, null, null, null, null, null, null, "DATE", "DATETIME", "TIME", 
+            "IDENTIFIER", "DELIMITEDIDENTIFIER", "STRING", "NUMBER", "WS", "COMMENT", 
+            "LINE_COMMENT"
+        };
+    }
+    private static final String[] _SYMBOLIC_NAMES = makeSymbolicNames();
     public static final Vocabulary VOCABULARY = new VocabularyImpl(_LITERAL_NAMES, _SYMBOLIC_NAMES);
 
     /**
@@ -80,180 +107,212 @@ public Vocabulary getVocabulary() {
         return VOCABULARY;
     }
 
+
     public FHIRPathLexer(CharStream input) {
         super(input);
-        _interp = new LexerATNSimulator(this, _ATN, _decisionToDFA, _sharedContextCache);
+        _interp = new LexerATNSimulator(this,_ATN,_decisionToDFA,_sharedContextCache);
     }
 
     @Override
-    public String getGrammarFileName() {
-        return "FHIRPath.g4";
-    }
+    public String getGrammarFileName() { return "FHIRPath.g4"; }
 
     @Override
-    public String[] getRuleNames() {
-        return ruleNames;
-    }
+    public String[] getRuleNames() { return ruleNames; }
 
     @Override
-    public String getSerializedATN() {
-        return _serializedATN;
-    }
+    public String getSerializedATN() { return _serializedATN; }
 
     @Override
-    public String[] getModeNames() {
-        return modeNames;
-    }
+    public String[] getChannelNames() { return channelNames; }
 
     @Override
-    public ATN getATN() {
-        return _ATN;
-    }
+    public String[] getModeNames() { return modeNames; }
+
+    @Override
+    public ATN getATN() { return _ATN; }
 
-    public static final String _serializedATN = "\3\u0430\ud6d1\u8206\uad2d\u4417\uaef1\u8d80\uaadd\2A\u0203\b\1\4\2\t"
-            + "\2\4\3\t\3\4\4\t\4\4\5\t\5\4\6\t\6\4\7\t\7\4\b\t\b\4\t\t\t\4\n\t\n\4\13"
-            + "\t\13\4\f\t\f\4\r\t\r\4\16\t\16\4\17\t\17\4\20\t\20\4\21\t\21\4\22\t\22"
-            + "\4\23\t\23\4\24\t\24\4\25\t\25\4\26\t\26\4\27\t\27\4\30\t\30\4\31\t\31" + "\4\32\t\32\4\33\t\33\4\34\t\34\4\35\t\35\4\36\t\36\4\37\t\37\4 \t \4!"
-            + "\t!\4\"\t\"\4#\t#\4$\t$\4%\t%\4&\t&\4\'\t\'\4(\t(\4)\t)\4*\t*\4+\t+\4" + ",\t,\4-\t-\4.\t.\4/\t/\4\60\t\60\4\61\t\61\4\62\t\62\4\63\t\63\4\64\t"
-            + "\64\4\65\t\65\4\66\t\66\4\67\t\67\48\t8\49\t9\4:\t:\4;\t;\4<\t<\4=\t=" + "\4>\t>\4?\t?\4@\t@\4A\tA\4B\tB\4C\tC\4D\tD\3\2\3\2\3\3\3\3\3\4\3\4\3\5"
-            + "\3\5\3\6\3\6\3\7\3\7\3\b\3\b\3\t\3\t\3\t\3\t\3\n\3\n\3\n\3\n\3\13\3\13" + "\3\f\3\f\3\f\3\r\3\r\3\r\3\16\3\16\3\17\3\17\3\17\3\20\3\20\3\21\3\21"
-            + "\3\22\3\22\3\22\3\23\3\23\3\24\3\24\3\25\3\25\3\25\3\26\3\26\3\26\3\27"
-            + "\3\27\3\27\3\30\3\30\3\30\3\30\3\30\3\30\3\30\3\30\3\30\3\31\3\31\3\31"
-            + "\3\31\3\32\3\32\3\32\3\33\3\33\3\33\3\33\3\34\3\34\3\34\3\34\3\34\3\34" + "\3\34\3\34\3\35\3\35\3\36\3\36\3\37\3\37\3 \3 \3!\3!\3!\3!\3!\3\"\3\""
-            + "\3\"\3\"\3\"\3\"\3#\3#\3$\3$\3$\3$\3$\3$\3%\3%\3%\3%\3%\3%\3%\3&\3&\3" + "&\3&\3&\3&\3&\3\'\3\'\3(\3(\3(\3(\3(\3)\3)\3)\3)\3)\3)\3*\3*\3*\3*\3*"
-            + "\3+\3+\3+\3+\3,\3,\3,\3,\3,\3-\3-\3-\3-\3-\3-\3-\3.\3.\3.\3.\3.\3.\3."
-            + "\3/\3/\3/\3/\3/\3/\3/\3/\3/\3/\3/\3/\3\60\3\60\3\60\3\60\3\60\3\60\3\61"
-            + "\3\61\3\61\3\61\3\61\3\61\3\61\3\62\3\62\3\62\3\62\3\62\3\62\3\63\3\63"
-            + "\3\63\3\63\3\63\3\64\3\64\3\64\3\64\3\64\3\64\3\65\3\65\3\65\3\65\3\65"
-            + "\3\65\3\65\3\65\3\66\3\66\3\66\3\66\3\66\3\66\3\66\3\66\3\67\3\67\3\67"
-            + "\3\67\3\67\3\67\3\67\3\67\3\67\3\67\3\67\3\67\3\67\38\38\38\38\38\38\3" + "8\38\38\38\38\38\38\58\u0183\n8\58\u0185\n8\58\u0187\n8\38\58\u018a\n"
-            + "8\39\39\39\39\3:\3:\3:\3:\3:\3:\3:\3:\3:\3:\6:\u019a\n:\r:\16:\u019b\5" + ":\u019e\n:\5:\u01a0\n:\5:\u01a2\n:\3:\3:\3:\3:\3:\3:\3:\5:\u01ab\n:\3"
-            + ";\5;\u01ae\n;\3;\7;\u01b1\n;\f;\16;\u01b4\13;\3<\3<\3<\7<\u01b9\n<\f<" + "\16<\u01bc\13<\3<\3<\3=\3=\3=\7=\u01c3\n=\f=\16=\u01c6\13=\3=\3=\3>\6"
-            + ">\u01cb\n>\r>\16>\u01cc\3>\3>\6>\u01d1\n>\r>\16>\u01d2\5>\u01d5\n>\3?"
-            + "\6?\u01d8\n?\r?\16?\u01d9\3?\3?\3@\3@\3@\3@\7@\u01e2\n@\f@\16@\u01e5\13"
-            + "@\3@\3@\3@\3@\3@\3A\3A\3A\3A\7A\u01f0\nA\fA\16A\u01f3\13A\3A\3A\3B\3B" + "\3B\5B\u01fa\nB\3C\3C\3C\3C\3C\3C\3D\3D\5\u01ba\u01c4\u01e3\2E\3\3\5\4"
-            + "\7\5\t\6\13\7\r\b\17\t\21\n\23\13\25\f\27\r\31\16\33\17\35\20\37\21!\22"
-            + "#\23%\24\'\25)\26+\27-\30/\31\61\32\63\33\65\34\67\359\36;\37= ?!A\"C" + "#E$G%I&K\'M(O)Q*S+U,W-Y.[/]\60_\61a\62c\63e\64g\65i\66k\67m8o9q:s\2u;"
-            + "w<y={>}?\177@\u0081A\u0083\2\u0085\2\u0087\2\3\2\n\3\2\62;\4\2--//\5\2" + "C\\aac|\6\2\62;C\\aac|\5\2\13\f\17\17\"\"\4\2\f\f\17\17\n\2))\61\61^^"
-            + "bbhhppttvv\5\2\62;CHch\u0214\2\3\3\2\2\2\2\5\3\2\2\2\2\7\3\2\2\2\2\t\3"
-            + "\2\2\2\2\13\3\2\2\2\2\r\3\2\2\2\2\17\3\2\2\2\2\21\3\2\2\2\2\23\3\2\2\2"
-            + "\2\25\3\2\2\2\2\27\3\2\2\2\2\31\3\2\2\2\2\33\3\2\2\2\2\35\3\2\2\2\2\37" + "\3\2\2\2\2!\3\2\2\2\2#\3\2\2\2\2%\3\2\2\2\2\'\3\2\2\2\2)\3\2\2\2\2+\3"
-            + "\2\2\2\2-\3\2\2\2\2/\3\2\2\2\2\61\3\2\2\2\2\63\3\2\2\2\2\65\3\2\2\2\2" + "\67\3\2\2\2\29\3\2\2\2\2;\3\2\2\2\2=\3\2\2\2\2?\3\2\2\2\2A\3\2\2\2\2C"
-            + "\3\2\2\2\2E\3\2\2\2\2G\3\2\2\2\2I\3\2\2\2\2K\3\2\2\2\2M\3\2\2\2\2O\3\2"
-            + "\2\2\2Q\3\2\2\2\2S\3\2\2\2\2U\3\2\2\2\2W\3\2\2\2\2Y\3\2\2\2\2[\3\2\2\2" + "\2]\3\2\2\2\2_\3\2\2\2\2a\3\2\2\2\2c\3\2\2\2\2e\3\2\2\2\2g\3\2\2\2\2i"
-            + "\3\2\2\2\2k\3\2\2\2\2m\3\2\2\2\2o\3\2\2\2\2q\3\2\2\2\2u\3\2\2\2\2w\3\2" + "\2\2\2y\3\2\2\2\2{\3\2\2\2\2}\3\2\2\2\2\177\3\2\2\2\2\u0081\3\2\2\2\3"
-            + "\u0089\3\2\2\2\5\u008b\3\2\2\2\7\u008d\3\2\2\2\t\u008f\3\2\2\2\13\u0091"
-            + "\3\2\2\2\r\u0093\3\2\2\2\17\u0095\3\2\2\2\21\u0097\3\2\2\2\23\u009b\3" + "\2\2\2\25\u009f\3\2\2\2\27\u00a1\3\2\2\2\31\u00a4\3\2\2\2\33\u00a7\3\2"
-            + "\2\2\35\u00a9\3\2\2\2\37\u00ac\3\2\2\2!\u00ae\3\2\2\2#\u00b0\3\2\2\2%" + "\u00b3\3\2\2\2\'\u00b5\3\2\2\2)\u00b7\3\2\2\2+\u00ba\3\2\2\2-\u00bd\3"
-            + "\2\2\2/\u00c0\3\2\2\2\61\u00c9\3\2\2\2\63\u00cd\3\2\2\2\65\u00d0\3\2\2"
-            + "\2\67\u00d4\3\2\2\29\u00dc\3\2\2\2;\u00de\3\2\2\2=\u00e0\3\2\2\2?\u00e2"
-            + "\3\2\2\2A\u00e4\3\2\2\2C\u00e9\3\2\2\2E\u00ef\3\2\2\2G\u00f1\3\2\2\2I" + "\u00f7\3\2\2\2K\u00fe\3\2\2\2M\u0105\3\2\2\2O\u0107\3\2\2\2Q\u010c\3\2"
-            + "\2\2S\u0112\3\2\2\2U\u0117\3\2\2\2W\u011b\3\2\2\2Y\u0120\3\2\2\2[\u0127"
-            + "\3\2\2\2]\u012e\3\2\2\2_\u013a\3\2\2\2a\u0140\3\2\2\2c\u0147\3\2\2\2e" + "\u014d\3\2\2\2g\u0152\3\2\2\2i\u0158\3\2\2\2k\u0160\3\2\2\2m\u0168\3\2"
-            + "\2\2o\u0175\3\2\2\2q\u018b\3\2\2\2s\u018f\3\2\2\2u\u01ad\3\2\2\2w\u01b5"
-            + "\3\2\2\2y\u01bf\3\2\2\2{\u01ca\3\2\2\2}\u01d7\3\2\2\2\177\u01dd\3\2\2"
-            + "\2\u0081\u01eb\3\2\2\2\u0083\u01f6\3\2\2\2\u0085\u01fb\3\2\2\2\u0087\u0201"
-            + "\3\2\2\2\u0089\u008a\7\60\2\2\u008a\4\3\2\2\2\u008b\u008c\7]\2\2\u008c"
-            + "\6\3\2\2\2\u008d\u008e\7_\2\2\u008e\b\3\2\2\2\u008f\u0090\7-\2\2\u0090"
-            + "\n\3\2\2\2\u0091\u0092\7/\2\2\u0092\f\3\2\2\2\u0093\u0094\7,\2\2\u0094"
-            + "\16\3\2\2\2\u0095\u0096\7\61\2\2\u0096\20\3\2\2\2\u0097\u0098\7f\2\2\u0098"
-            + "\u0099\7k\2\2\u0099\u009a\7x\2\2\u009a\22\3\2\2\2\u009b\u009c\7o\2\2\u009c"
-            + "\u009d\7q\2\2\u009d\u009e\7f\2\2\u009e\24\3\2\2\2\u009f\u00a0\7(\2\2\u00a0"
-            + "\26\3\2\2\2\u00a1\u00a2\7k\2\2\u00a2\u00a3\7u\2\2\u00a3\30\3\2\2\2\u00a4"
-            + "\u00a5\7c\2\2\u00a5\u00a6\7u\2\2\u00a6\32\3\2\2\2\u00a7\u00a8\7~\2\2\u00a8"
-            + "\34\3\2\2\2\u00a9\u00aa\7>\2\2\u00aa\u00ab\7?\2\2\u00ab\36\3\2\2\2\u00ac"
-            + "\u00ad\7>\2\2\u00ad \3\2\2\2\u00ae\u00af\7@\2\2\u00af\"\3\2\2\2\u00b0"
-            + "\u00b1\7@\2\2\u00b1\u00b2\7?\2\2\u00b2$\3\2\2\2\u00b3\u00b4\7?\2\2\u00b4"
-            + "&\3\2\2\2\u00b5\u00b6\7\u0080\2\2\u00b6(\3\2\2\2\u00b7\u00b8\7#\2\2\u00b8"
-            + "\u00b9\7?\2\2\u00b9*\3\2\2\2\u00ba\u00bb\7#\2\2\u00bb\u00bc\7\u0080\2" + "\2\u00bc,\3\2\2\2\u00bd\u00be\7k\2\2\u00be\u00bf\7p\2\2\u00bf.\3\2\2\2"
-            + "\u00c0\u00c1\7e\2\2\u00c1\u00c2\7q\2\2\u00c2\u00c3\7p\2\2\u00c3\u00c4" + "\7v\2\2\u00c4\u00c5\7c\2\2\u00c5\u00c6\7k\2\2\u00c6\u00c7\7p\2\2\u00c7"
-            + "\u00c8\7u\2\2\u00c8\60\3\2\2\2\u00c9\u00ca\7c\2\2\u00ca\u00cb\7p\2\2\u00cb"
-            + "\u00cc\7f\2\2\u00cc\62\3\2\2\2\u00cd\u00ce\7q\2\2\u00ce\u00cf\7t\2\2\u00cf"
-            + "\64\3\2\2\2\u00d0\u00d1\7z\2\2\u00d1\u00d2\7q\2\2\u00d2\u00d3\7t\2\2\u00d3"
-            + "\66\3\2\2\2\u00d4\u00d5\7k\2\2\u00d5\u00d6\7o\2\2\u00d6\u00d7\7r\2\2\u00d7"
-            + "\u00d8\7n\2\2\u00d8\u00d9\7k\2\2\u00d9\u00da\7g\2\2\u00da\u00db\7u\2\2"
-            + "\u00db8\3\2\2\2\u00dc\u00dd\7*\2\2\u00dd:\3\2\2\2\u00de\u00df\7+\2\2\u00df"
-            + "<\3\2\2\2\u00e0\u00e1\7}\2\2\u00e1>\3\2\2\2\u00e2\u00e3\7\177\2\2\u00e3"
-            + "@\3\2\2\2\u00e4\u00e5\7v\2\2\u00e5\u00e6\7t\2\2\u00e6\u00e7\7w\2\2\u00e7"
-            + "\u00e8\7g\2\2\u00e8B\3\2\2\2\u00e9\u00ea\7h\2\2\u00ea\u00eb\7c\2\2\u00eb"
-            + "\u00ec\7n\2\2\u00ec\u00ed\7u\2\2\u00ed\u00ee\7g\2\2\u00eeD\3\2\2\2\u00ef"
-            + "\u00f0\7\'\2\2\u00f0F\3\2\2\2\u00f1\u00f2\7&\2\2\u00f2\u00f3\7v\2\2\u00f3"
-            + "\u00f4\7j\2\2\u00f4\u00f5\7k\2\2\u00f5\u00f6\7u\2\2\u00f6H\3\2\2\2\u00f7"
-            + "\u00f8\7&\2\2\u00f8\u00f9\7k\2\2\u00f9\u00fa\7p\2\2\u00fa\u00fb\7f\2\2"
-            + "\u00fb\u00fc\7g\2\2\u00fc\u00fd\7z\2\2\u00fdJ\3\2\2\2\u00fe\u00ff\7&\2"
-            + "\2\u00ff\u0100\7v\2\2\u0100\u0101\7q\2\2\u0101\u0102\7v\2\2\u0102\u0103"
-            + "\7c\2\2\u0103\u0104\7n\2\2\u0104L\3\2\2\2\u0105\u0106\7.\2\2\u0106N\3" + "\2\2\2\u0107\u0108\7{\2\2\u0108\u0109\7g\2\2\u0109\u010a\7c\2\2\u010a"
-            + "\u010b\7t\2\2\u010bP\3\2\2\2\u010c\u010d\7o\2\2\u010d\u010e\7q\2\2\u010e"
-            + "\u010f\7p\2\2\u010f\u0110\7v\2\2\u0110\u0111\7j\2\2\u0111R\3\2\2\2\u0112"
-            + "\u0113\7y\2\2\u0113\u0114\7g\2\2\u0114\u0115\7g\2\2\u0115\u0116\7m\2\2"
-            + "\u0116T\3\2\2\2\u0117\u0118\7f\2\2\u0118\u0119\7c\2\2\u0119\u011a\7{\2" + "\2\u011aV\3\2\2\2\u011b\u011c\7j\2\2\u011c\u011d\7q\2\2\u011d\u011e\7"
-            + "w\2\2\u011e\u011f\7t\2\2\u011fX\3\2\2\2\u0120\u0121\7o\2\2\u0121\u0122"
-            + "\7k\2\2\u0122\u0123\7p\2\2\u0123\u0124\7w\2\2\u0124\u0125\7v\2\2\u0125"
-            + "\u0126\7g\2\2\u0126Z\3\2\2\2\u0127\u0128\7u\2\2\u0128\u0129\7g\2\2\u0129"
-            + "\u012a\7e\2\2\u012a\u012b\7q\2\2\u012b\u012c\7p\2\2\u012c\u012d\7f\2\2" + "\u012d\\\3\2\2\2\u012e\u012f\7o\2\2\u012f\u0130\7k\2\2\u0130\u0131\7n"
-            + "\2\2\u0131\u0132\7n\2\2\u0132\u0133\7k\2\2\u0133\u0134\7u\2\2\u0134\u0135"
-            + "\7g\2\2\u0135\u0136\7e\2\2\u0136\u0137\7q\2\2\u0137\u0138\7p\2\2\u0138"
-            + "\u0139\7f\2\2\u0139^\3\2\2\2\u013a\u013b\7{\2\2\u013b\u013c\7g\2\2\u013c"
-            + "\u013d\7c\2\2\u013d\u013e\7t\2\2\u013e\u013f\7u\2\2\u013f`\3\2\2\2\u0140"
-            + "\u0141\7o\2\2\u0141\u0142\7q\2\2\u0142\u0143\7p\2\2\u0143\u0144\7v\2\2"
-            + "\u0144\u0145\7j\2\2\u0145\u0146\7u\2\2\u0146b\3\2\2\2\u0147\u0148\7y\2"
-            + "\2\u0148\u0149\7g\2\2\u0149\u014a\7g\2\2\u014a\u014b\7m\2\2\u014b\u014c"
-            + "\7u\2\2\u014cd\3\2\2\2\u014d\u014e\7f\2\2\u014e\u014f\7c\2\2\u014f\u0150"
-            + "\7{\2\2\u0150\u0151\7u\2\2\u0151f\3\2\2\2\u0152\u0153\7j\2\2\u0153\u0154"
-            + "\7q\2\2\u0154\u0155\7w\2\2\u0155\u0156\7t\2\2\u0156\u0157\7u\2\2\u0157"
-            + "h\3\2\2\2\u0158\u0159\7o\2\2\u0159\u015a\7k\2\2\u015a\u015b\7p\2\2\u015b"
-            + "\u015c\7w\2\2\u015c\u015d\7v\2\2\u015d\u015e\7g\2\2\u015e\u015f\7u\2\2"
-            + "\u015fj\3\2\2\2\u0160\u0161\7u\2\2\u0161\u0162\7g\2\2\u0162\u0163\7e\2"
-            + "\2\u0163\u0164\7q\2\2\u0164\u0165\7p\2\2\u0165\u0166\7f\2\2\u0166\u0167"
-            + "\7u\2\2\u0167l\3\2\2\2\u0168\u0169\7o\2\2\u0169\u016a\7k\2\2\u016a\u016b"
-            + "\7n\2\2\u016b\u016c\7n\2\2\u016c\u016d\7k\2\2\u016d\u016e\7u\2\2\u016e"
-            + "\u016f\7g\2\2\u016f\u0170\7e\2\2\u0170\u0171\7q\2\2\u0171\u0172\7p\2\2"
-            + "\u0172\u0173\7f\2\2\u0173\u0174\7u\2\2\u0174n\3\2\2\2\u0175\u0176\7B\2"
-            + "\2\u0176\u0177\t\2\2\2\u0177\u0178\t\2\2\2\u0178\u0179\t\2\2\2\u0179\u0186"
-            + "\t\2\2\2\u017a\u017b\7/\2\2\u017b\u017c\t\2\2\2\u017c\u0184\t\2\2\2\u017d"
-            + "\u017e\7/\2\2\u017e\u017f\t\2\2\2\u017f\u0182\t\2\2\2\u0180\u0181\7V\2"
-            + "\2\u0181\u0183\5s:\2\u0182\u0180\3\2\2\2\u0182\u0183\3\2\2\2\u0183\u0185"
-            + "\3\2\2\2\u0184\u017d\3\2\2\2\u0184\u0185\3\2\2\2\u0185\u0187\3\2\2\2\u0186"
-            + "\u017a\3\2\2\2\u0186\u0187\3\2\2\2\u0187\u0189\3\2\2\2\u0188\u018a\7\\"
-            + "\2\2\u0189\u0188\3\2\2\2\u0189\u018a\3\2\2\2\u018ap\3\2\2\2\u018b\u018c"
-            + "\7B\2\2\u018c\u018d\7V\2\2\u018d\u018e\5s:\2\u018er\3\2\2\2\u018f\u0190"
-            + "\t\2\2\2\u0190\u01a1\t\2\2\2\u0191\u0192\7<\2\2\u0192\u0193\t\2\2\2\u0193"
-            + "\u019f\t\2\2\2\u0194\u0195\7<\2\2\u0195\u0196\t\2\2\2\u0196\u019d\t\2"
-            + "\2\2\u0197\u0199\7\60\2\2\u0198\u019a\t\2\2\2\u0199\u0198\3\2\2\2\u019a"
-            + "\u019b\3\2\2\2\u019b\u0199\3\2\2\2\u019b\u019c\3\2\2\2\u019c\u019e\3\2"
-            + "\2\2\u019d\u0197\3\2\2\2\u019d\u019e\3\2\2\2\u019e\u01a0\3\2\2\2\u019f"
-            + "\u0194\3\2\2\2\u019f\u01a0\3\2\2\2\u01a0\u01a2\3\2\2\2\u01a1\u0191\3\2"
-            + "\2\2\u01a1\u01a2\3\2\2\2\u01a2\u01aa\3\2\2\2\u01a3\u01ab\7\\\2\2\u01a4" + "\u01a5\t\3\2\2\u01a5\u01a6\t\2\2\2\u01a6\u01a7\t\2\2\2\u01a7\u01a8\7<"
-            + "\2\2\u01a8\u01a9\t\2\2\2\u01a9\u01ab\t\2\2\2\u01aa\u01a3\3\2\2\2\u01aa" + "\u01a4\3\2\2\2\u01aa\u01ab\3\2\2\2\u01abt\3\2\2\2\u01ac\u01ae\t\4\2\2"
-            + "\u01ad\u01ac\3\2\2\2\u01ae\u01b2\3\2\2\2\u01af\u01b1\t\5\2\2\u01b0\u01af"
-            + "\3\2\2\2\u01b1\u01b4\3\2\2\2\u01b2\u01b0\3\2\2\2\u01b2\u01b3\3\2\2\2\u01b3"
-            + "v\3\2\2\2\u01b4\u01b2\3\2\2\2\u01b5\u01ba\7b\2\2\u01b6\u01b9\5\u0083B" + "\2\u01b7\u01b9\13\2\2\2\u01b8\u01b6\3\2\2\2\u01b8\u01b7\3\2\2\2\u01b9"
-            + "\u01bc\3\2\2\2\u01ba\u01bb\3\2\2\2\u01ba\u01b8\3\2\2\2\u01bb\u01bd\3\2"
-            + "\2\2\u01bc\u01ba\3\2\2\2\u01bd\u01be\7b\2\2\u01bex\3\2\2\2\u01bf\u01c4" + "\7)\2\2\u01c0\u01c3\5\u0083B\2\u01c1\u01c3\13\2\2\2\u01c2\u01c0\3\2\2"
-            + "\2\u01c2\u01c1\3\2\2\2\u01c3\u01c6\3\2\2\2\u01c4\u01c5\3\2\2\2\u01c4\u01c2"
-            + "\3\2\2\2\u01c5\u01c7\3\2\2\2\u01c6\u01c4\3\2\2\2\u01c7\u01c8\7)\2\2\u01c8"
-            + "z\3\2\2\2\u01c9\u01cb\t\2\2\2\u01ca\u01c9\3\2\2\2\u01cb\u01cc\3\2\2\2"
-            + "\u01cc\u01ca\3\2\2\2\u01cc\u01cd\3\2\2\2\u01cd\u01d4\3\2\2\2\u01ce\u01d0"
-            + "\7\60\2\2\u01cf\u01d1\t\2\2\2\u01d0\u01cf\3\2\2\2\u01d1\u01d2\3\2\2\2"
-            + "\u01d2\u01d0\3\2\2\2\u01d2\u01d3\3\2\2\2\u01d3\u01d5\3\2\2\2\u01d4\u01ce"
-            + "\3\2\2\2\u01d4\u01d5\3\2\2\2\u01d5|\3\2\2\2\u01d6\u01d8\t\6\2\2\u01d7" + "\u01d6\3\2\2\2\u01d8\u01d9\3\2\2\2\u01d9\u01d7\3\2\2\2\u01d9\u01da\3\2"
-            + "\2\2\u01da\u01db\3\2\2\2\u01db\u01dc\b?\2\2\u01dc~\3\2\2\2\u01dd\u01de" + "\7\61\2\2\u01de\u01df\7,\2\2\u01df\u01e3\3\2\2\2\u01e0\u01e2\13\2\2\2"
-            + "\u01e1\u01e0\3\2\2\2\u01e2\u01e5\3\2\2\2\u01e3\u01e4\3\2\2\2\u01e3\u01e1"
-            + "\3\2\2\2\u01e4\u01e6\3\2\2\2\u01e5\u01e3\3\2\2\2\u01e6\u01e7\7,\2\2\u01e7"
-            + "\u01e8\7\61\2\2\u01e8\u01e9\3\2\2\2\u01e9\u01ea\b@\2\2\u01ea\u0080\3\2"
-            + "\2\2\u01eb\u01ec\7\61\2\2\u01ec\u01ed\7\61\2\2\u01ed\u01f1\3\2\2\2\u01ee"
-            + "\u01f0\n\7\2\2\u01ef\u01ee\3\2\2\2\u01f0\u01f3\3\2\2\2\u01f1\u01ef\3\2"
-            + "\2\2\u01f1\u01f2\3\2\2\2\u01f2\u01f4\3\2\2\2\u01f3\u01f1\3\2\2\2\u01f4"
-            + "\u01f5\bA\2\2\u01f5\u0082\3\2\2\2\u01f6\u01f9\7^\2\2\u01f7\u01fa\t\b\2"
-            + "\2\u01f8\u01fa\5\u0085C\2\u01f9\u01f7\3\2\2\2\u01f9\u01f8\3\2\2\2\u01fa"
-            + "\u0084\3\2\2\2\u01fb\u01fc\7w\2\2\u01fc\u01fd\5\u0087D\2\u01fd\u01fe\5" + "\u0087D\2\u01fe\u01ff\5\u0087D\2\u01ff\u0200\5\u0087D\2\u0200\u0086\3"
-            + "\2\2\2\u0201\u0202\t\t\2\2\u0202\u0088\3\2\2\2\32\2\u0182\u0184\u0186"
-            + "\u0189\u019b\u019d\u019f\u01a1\u01aa\u01ad\u01b0\u01b2\u01b8\u01ba\u01c2" + "\u01c4\u01cc\u01d2\u01d4\u01d9\u01e3\u01f1\u01f9\3\2\3\2";
-    public static final ATN _ATN = new ATNDeserializer().deserialize(_serializedATN.toCharArray());
+    public static final String _serializedATN =
+        "\3\u608b\ua72a\u8133\ub9ed\u417c\u3be7\u7786\u5964\2B\u020d\b\1\4\2\t"+
+        "\2\4\3\t\3\4\4\t\4\4\5\t\5\4\6\t\6\4\7\t\7\4\b\t\b\4\t\t\t\4\n\t\n\4\13"+
+        "\t\13\4\f\t\f\4\r\t\r\4\16\t\16\4\17\t\17\4\20\t\20\4\21\t\21\4\22\t\22"+
+        "\4\23\t\23\4\24\t\24\4\25\t\25\4\26\t\26\4\27\t\27\4\30\t\30\4\31\t\31"+
+        "\4\32\t\32\4\33\t\33\4\34\t\34\4\35\t\35\4\36\t\36\4\37\t\37\4 \t \4!"+
+        "\t!\4\"\t\"\4#\t#\4$\t$\4%\t%\4&\t&\4\'\t\'\4(\t(\4)\t)\4*\t*\4+\t+\4"+
+        ",\t,\4-\t-\4.\t.\4/\t/\4\60\t\60\4\61\t\61\4\62\t\62\4\63\t\63\4\64\t"+
+        "\64\4\65\t\65\4\66\t\66\4\67\t\67\48\t8\49\t9\4:\t:\4;\t;\4<\t<\4=\t="+
+        "\4>\t>\4?\t?\4@\t@\4A\tA\4B\tB\4C\tC\4D\tD\4E\tE\4F\tF\4G\tG\3\2\3\2\3"+
+        "\3\3\3\3\4\3\4\3\5\3\5\3\6\3\6\3\7\3\7\3\b\3\b\3\t\3\t\3\t\3\t\3\n\3\n"+
+        "\3\n\3\n\3\13\3\13\3\f\3\f\3\f\3\r\3\r\3\r\3\16\3\16\3\17\3\17\3\17\3"+
+        "\20\3\20\3\21\3\21\3\22\3\22\3\22\3\23\3\23\3\24\3\24\3\25\3\25\3\25\3"+
+        "\26\3\26\3\26\3\27\3\27\3\27\3\30\3\30\3\30\3\30\3\30\3\30\3\30\3\30\3"+
+        "\30\3\31\3\31\3\31\3\31\3\32\3\32\3\32\3\33\3\33\3\33\3\33\3\34\3\34\3"+
+        "\34\3\34\3\34\3\34\3\34\3\34\3\35\3\35\3\36\3\36\3\37\3\37\3 \3 \3!\3"+
+        "!\3!\3!\3!\3\"\3\"\3\"\3\"\3\"\3\"\3#\3#\3$\3$\3$\3$\3$\3$\3%\3%\3%\3"+
+        "%\3%\3%\3%\3&\3&\3&\3&\3&\3&\3&\3\'\3\'\3(\3(\3(\3(\3(\3)\3)\3)\3)\3)"+
+        "\3)\3*\3*\3*\3*\3*\3+\3+\3+\3+\3,\3,\3,\3,\3,\3-\3-\3-\3-\3-\3-\3-\3."+
+        "\3.\3.\3.\3.\3.\3.\3/\3/\3/\3/\3/\3/\3/\3/\3/\3/\3/\3/\3\60\3\60\3\60"+
+        "\3\60\3\60\3\60\3\61\3\61\3\61\3\61\3\61\3\61\3\61\3\62\3\62\3\62\3\62"+
+        "\3\62\3\62\3\63\3\63\3\63\3\63\3\63\3\64\3\64\3\64\3\64\3\64\3\64\3\65"+
+        "\3\65\3\65\3\65\3\65\3\65\3\65\3\65\3\66\3\66\3\66\3\66\3\66\3\66\3\66"+
+        "\3\66\3\67\3\67\3\67\3\67\3\67\3\67\3\67\3\67\3\67\3\67\3\67\3\67\3\67"+
+        "\38\38\38\39\39\39\39\39\59\u0184\n9\59\u0186\n9\3:\3:\3:\3:\3;\3;\3;"+
+        "\3;\3;\3;\3;\3;\3;\3;\5;\u0196\n;\5;\u0198\n;\3<\3<\3<\3<\3<\3<\3<\3<"+
+        "\3<\3<\6<\u01a4\n<\r<\16<\u01a5\5<\u01a8\n<\5<\u01aa\n<\5<\u01ac\n<\3"+
+        "=\3=\3=\3=\3=\3=\3=\5=\u01b5\n=\3>\5>\u01b8\n>\3>\7>\u01bb\n>\f>\16>\u01be"+
+        "\13>\3?\3?\3?\7?\u01c3\n?\f?\16?\u01c6\13?\3?\3?\3@\3@\3@\7@\u01cd\n@"+
+        "\f@\16@\u01d0\13@\3@\3@\3A\6A\u01d5\nA\rA\16A\u01d6\3A\3A\6A\u01db\nA"+
+        "\rA\16A\u01dc\5A\u01df\nA\3B\6B\u01e2\nB\rB\16B\u01e3\3B\3B\3C\3C\3C\3"+
+        "C\7C\u01ec\nC\fC\16C\u01ef\13C\3C\3C\3C\3C\3C\3D\3D\3D\3D\7D\u01fa\nD"+
+        "\fD\16D\u01fd\13D\3D\3D\3E\3E\3E\5E\u0204\nE\3F\3F\3F\3F\3F\3F\3G\3G\5"+
+        "\u01c4\u01ce\u01ed\2H\3\3\5\4\7\5\t\6\13\7\r\b\17\t\21\n\23\13\25\f\27"+
+        "\r\31\16\33\17\35\20\37\21!\22#\23%\24\'\25)\26+\27-\30/\31\61\32\63\33"+
+        "\65\34\67\359\36;\37= ?!A\"C#E$G%I&K\'M(O)Q*S+U,W-Y.[/]\60_\61a\62c\63"+
+        "e\64g\65i\66k\67m8o9q:s;u\2w\2y\2{<}=\177>\u0081?\u0083@\u0085A\u0087"+
+        "B\u0089\2\u008b\2\u008d\2\3\2\n\3\2\62;\4\2--//\5\2C\\aac|\6\2\62;C\\"+
+        "aac|\5\2\13\f\17\17\"\"\4\2\f\f\17\17\n\2))\61\61^^bbhhppttvv\5\2\62;"+
+        "CHch\2\u021b\2\3\3\2\2\2\2\5\3\2\2\2\2\7\3\2\2\2\2\t\3\2\2\2\2\13\3\2"+
+        "\2\2\2\r\3\2\2\2\2\17\3\2\2\2\2\21\3\2\2\2\2\23\3\2\2\2\2\25\3\2\2\2\2"+
+        "\27\3\2\2\2\2\31\3\2\2\2\2\33\3\2\2\2\2\35\3\2\2\2\2\37\3\2\2\2\2!\3\2"+
+        "\2\2\2#\3\2\2\2\2%\3\2\2\2\2\'\3\2\2\2\2)\3\2\2\2\2+\3\2\2\2\2-\3\2\2"+
+        "\2\2/\3\2\2\2\2\61\3\2\2\2\2\63\3\2\2\2\2\65\3\2\2\2\2\67\3\2\2\2\29\3"+
+        "\2\2\2\2;\3\2\2\2\2=\3\2\2\2\2?\3\2\2\2\2A\3\2\2\2\2C\3\2\2\2\2E\3\2\2"+
+        "\2\2G\3\2\2\2\2I\3\2\2\2\2K\3\2\2\2\2M\3\2\2\2\2O\3\2\2\2\2Q\3\2\2\2\2"+
+        "S\3\2\2\2\2U\3\2\2\2\2W\3\2\2\2\2Y\3\2\2\2\2[\3\2\2\2\2]\3\2\2\2\2_\3"+
+        "\2\2\2\2a\3\2\2\2\2c\3\2\2\2\2e\3\2\2\2\2g\3\2\2\2\2i\3\2\2\2\2k\3\2\2"+
+        "\2\2m\3\2\2\2\2o\3\2\2\2\2q\3\2\2\2\2s\3\2\2\2\2{\3\2\2\2\2}\3\2\2\2\2"+
+        "\177\3\2\2\2\2\u0081\3\2\2\2\2\u0083\3\2\2\2\2\u0085\3\2\2\2\2\u0087\3"+
+        "\2\2\2\3\u008f\3\2\2\2\5\u0091\3\2\2\2\7\u0093\3\2\2\2\t\u0095\3\2\2\2"+
+        "\13\u0097\3\2\2\2\r\u0099\3\2\2\2\17\u009b\3\2\2\2\21\u009d\3\2\2\2\23"+
+        "\u00a1\3\2\2\2\25\u00a5\3\2\2\2\27\u00a7\3\2\2\2\31\u00aa\3\2\2\2\33\u00ad"+
+        "\3\2\2\2\35\u00af\3\2\2\2\37\u00b2\3\2\2\2!\u00b4\3\2\2\2#\u00b6\3\2\2"+
+        "\2%\u00b9\3\2\2\2\'\u00bb\3\2\2\2)\u00bd\3\2\2\2+\u00c0\3\2\2\2-\u00c3"+
+        "\3\2\2\2/\u00c6\3\2\2\2\61\u00cf\3\2\2\2\63\u00d3\3\2\2\2\65\u00d6\3\2"+
+        "\2\2\67\u00da\3\2\2\29\u00e2\3\2\2\2;\u00e4\3\2\2\2=\u00e6\3\2\2\2?\u00e8"+
+        "\3\2\2\2A\u00ea\3\2\2\2C\u00ef\3\2\2\2E\u00f5\3\2\2\2G\u00f7\3\2\2\2I"+
+        "\u00fd\3\2\2\2K\u0104\3\2\2\2M\u010b\3\2\2\2O\u010d\3\2\2\2Q\u0112\3\2"+
+        "\2\2S\u0118\3\2\2\2U\u011d\3\2\2\2W\u0121\3\2\2\2Y\u0126\3\2\2\2[\u012d"+
+        "\3\2\2\2]\u0134\3\2\2\2_\u0140\3\2\2\2a\u0146\3\2\2\2c\u014d\3\2\2\2e"+
+        "\u0153\3\2\2\2g\u0158\3\2\2\2i\u015e\3\2\2\2k\u0166\3\2\2\2m\u016e\3\2"+
+        "\2\2o\u017b\3\2\2\2q\u017e\3\2\2\2s\u0187\3\2\2\2u\u018b\3\2\2\2w\u0199"+
+        "\3\2\2\2y\u01b4\3\2\2\2{\u01b7\3\2\2\2}\u01bf\3\2\2\2\177\u01c9\3\2\2"+
+        "\2\u0081\u01d4\3\2\2\2\u0083\u01e1\3\2\2\2\u0085\u01e7\3\2\2\2\u0087\u01f5"+
+        "\3\2\2\2\u0089\u0200\3\2\2\2\u008b\u0205\3\2\2\2\u008d\u020b\3\2\2\2\u008f"+
+        "\u0090\7\60\2\2\u0090\4\3\2\2\2\u0091\u0092\7]\2\2\u0092\6\3\2\2\2\u0093"+
+        "\u0094\7_\2\2\u0094\b\3\2\2\2\u0095\u0096\7-\2\2\u0096\n\3\2\2\2\u0097"+
+        "\u0098\7/\2\2\u0098\f\3\2\2\2\u0099\u009a\7,\2\2\u009a\16\3\2\2\2\u009b"+
+        "\u009c\7\61\2\2\u009c\20\3\2\2\2\u009d\u009e\7f\2\2\u009e\u009f\7k\2\2"+
+        "\u009f\u00a0\7x\2\2\u00a0\22\3\2\2\2\u00a1\u00a2\7o\2\2\u00a2\u00a3\7"+
+        "q\2\2\u00a3\u00a4\7f\2\2\u00a4\24\3\2\2\2\u00a5\u00a6\7(\2\2\u00a6\26"+
+        "\3\2\2\2\u00a7\u00a8\7k\2\2\u00a8\u00a9\7u\2\2\u00a9\30\3\2\2\2\u00aa"+
+        "\u00ab\7c\2\2\u00ab\u00ac\7u\2\2\u00ac\32\3\2\2\2\u00ad\u00ae\7~\2\2\u00ae"+
+        "\34\3\2\2\2\u00af\u00b0\7>\2\2\u00b0\u00b1\7?\2\2\u00b1\36\3\2\2\2\u00b2"+
+        "\u00b3\7>\2\2\u00b3 \3\2\2\2\u00b4\u00b5\7@\2\2\u00b5\"\3\2\2\2\u00b6"+
+        "\u00b7\7@\2\2\u00b7\u00b8\7?\2\2\u00b8$\3\2\2\2\u00b9\u00ba\7?\2\2\u00ba"+
+        "&\3\2\2\2\u00bb\u00bc\7\u0080\2\2\u00bc(\3\2\2\2\u00bd\u00be\7#\2\2\u00be"+
+        "\u00bf\7?\2\2\u00bf*\3\2\2\2\u00c0\u00c1\7#\2\2\u00c1\u00c2\7\u0080\2"+
+        "\2\u00c2,\3\2\2\2\u00c3\u00c4\7k\2\2\u00c4\u00c5\7p\2\2\u00c5.\3\2\2\2"+
+        "\u00c6\u00c7\7e\2\2\u00c7\u00c8\7q\2\2\u00c8\u00c9\7p\2\2\u00c9\u00ca"+
+        "\7v\2\2\u00ca\u00cb\7c\2\2\u00cb\u00cc\7k\2\2\u00cc\u00cd\7p\2\2\u00cd"+
+        "\u00ce\7u\2\2\u00ce\60\3\2\2\2\u00cf\u00d0\7c\2\2\u00d0\u00d1\7p\2\2\u00d1"+
+        "\u00d2\7f\2\2\u00d2\62\3\2\2\2\u00d3\u00d4\7q\2\2\u00d4\u00d5\7t\2\2\u00d5"+
+        "\64\3\2\2\2\u00d6\u00d7\7z\2\2\u00d7\u00d8\7q\2\2\u00d8\u00d9\7t\2\2\u00d9"+
+        "\66\3\2\2\2\u00da\u00db\7k\2\2\u00db\u00dc\7o\2\2\u00dc\u00dd\7r\2\2\u00dd"+
+        "\u00de\7n\2\2\u00de\u00df\7k\2\2\u00df\u00e0\7g\2\2\u00e0\u00e1\7u\2\2"+
+        "\u00e18\3\2\2\2\u00e2\u00e3\7*\2\2\u00e3:\3\2\2\2\u00e4\u00e5\7+\2\2\u00e5"+
+        "<\3\2\2\2\u00e6\u00e7\7}\2\2\u00e7>\3\2\2\2\u00e8\u00e9\7\177\2\2\u00e9"+
+        "@\3\2\2\2\u00ea\u00eb\7v\2\2\u00eb\u00ec\7t\2\2\u00ec\u00ed\7w\2\2\u00ed"+
+        "\u00ee\7g\2\2\u00eeB\3\2\2\2\u00ef\u00f0\7h\2\2\u00f0\u00f1\7c\2\2\u00f1"+
+        "\u00f2\7n\2\2\u00f2\u00f3\7u\2\2\u00f3\u00f4\7g\2\2\u00f4D\3\2\2\2\u00f5"+
+        "\u00f6\7\'\2\2\u00f6F\3\2\2\2\u00f7\u00f8\7&\2\2\u00f8\u00f9\7v\2\2\u00f9"+
+        "\u00fa\7j\2\2\u00fa\u00fb\7k\2\2\u00fb\u00fc\7u\2\2\u00fcH\3\2\2\2\u00fd"+
+        "\u00fe\7&\2\2\u00fe\u00ff\7k\2\2\u00ff\u0100\7p\2\2\u0100\u0101\7f\2\2"+
+        "\u0101\u0102\7g\2\2\u0102\u0103\7z\2\2\u0103J\3\2\2\2\u0104\u0105\7&\2"+
+        "\2\u0105\u0106\7v\2\2\u0106\u0107\7q\2\2\u0107\u0108\7v\2\2\u0108\u0109"+
+        "\7c\2\2\u0109\u010a\7n\2\2\u010aL\3\2\2\2\u010b\u010c\7.\2\2\u010cN\3"+
+        "\2\2\2\u010d\u010e\7{\2\2\u010e\u010f\7g\2\2\u010f\u0110\7c\2\2\u0110"+
+        "\u0111\7t\2\2\u0111P\3\2\2\2\u0112\u0113\7o\2\2\u0113\u0114\7q\2\2\u0114"+
+        "\u0115\7p\2\2\u0115\u0116\7v\2\2\u0116\u0117\7j\2\2\u0117R\3\2\2\2\u0118"+
+        "\u0119\7y\2\2\u0119\u011a\7g\2\2\u011a\u011b\7g\2\2\u011b\u011c\7m\2\2"+
+        "\u011cT\3\2\2\2\u011d\u011e\7f\2\2\u011e\u011f\7c\2\2\u011f\u0120\7{\2"+
+        "\2\u0120V\3\2\2\2\u0121\u0122\7j\2\2\u0122\u0123\7q\2\2\u0123\u0124\7"+
+        "w\2\2\u0124\u0125\7t\2\2\u0125X\3\2\2\2\u0126\u0127\7o\2\2\u0127\u0128"+
+        "\7k\2\2\u0128\u0129\7p\2\2\u0129\u012a\7w\2\2\u012a\u012b\7v\2\2\u012b"+
+        "\u012c\7g\2\2\u012cZ\3\2\2\2\u012d\u012e\7u\2\2\u012e\u012f\7g\2\2\u012f"+
+        "\u0130\7e\2\2\u0130\u0131\7q\2\2\u0131\u0132\7p\2\2\u0132\u0133\7f\2\2"+
+        "\u0133\\\3\2\2\2\u0134\u0135\7o\2\2\u0135\u0136\7k\2\2\u0136\u0137\7n"+
+        "\2\2\u0137\u0138\7n\2\2\u0138\u0139\7k\2\2\u0139\u013a\7u\2\2\u013a\u013b"+
+        "\7g\2\2\u013b\u013c\7e\2\2\u013c\u013d\7q\2\2\u013d\u013e\7p\2\2\u013e"+
+        "\u013f\7f\2\2\u013f^\3\2\2\2\u0140\u0141\7{\2\2\u0141\u0142\7g\2\2\u0142"+
+        "\u0143\7c\2\2\u0143\u0144\7t\2\2\u0144\u0145\7u\2\2\u0145`\3\2\2\2\u0146"+
+        "\u0147\7o\2\2\u0147\u0148\7q\2\2\u0148\u0149\7p\2\2\u0149\u014a\7v\2\2"+
+        "\u014a\u014b\7j\2\2\u014b\u014c\7u\2\2\u014cb\3\2\2\2\u014d\u014e\7y\2"+
+        "\2\u014e\u014f\7g\2\2\u014f\u0150\7g\2\2\u0150\u0151\7m\2\2\u0151\u0152"+
+        "\7u\2\2\u0152d\3\2\2\2\u0153\u0154\7f\2\2\u0154\u0155\7c\2\2\u0155\u0156"+
+        "\7{\2\2\u0156\u0157\7u\2\2\u0157f\3\2\2\2\u0158\u0159\7j\2\2\u0159\u015a"+
+        "\7q\2\2\u015a\u015b\7w\2\2\u015b\u015c\7t\2\2\u015c\u015d\7u\2\2\u015d"+
+        "h\3\2\2\2\u015e\u015f\7o\2\2\u015f\u0160\7k\2\2\u0160\u0161\7p\2\2\u0161"+
+        "\u0162\7w\2\2\u0162\u0163\7v\2\2\u0163\u0164\7g\2\2\u0164\u0165\7u\2\2"+
+        "\u0165j\3\2\2\2\u0166\u0167\7u\2\2\u0167\u0168\7g\2\2\u0168\u0169\7e\2"+
+        "\2\u0169\u016a\7q\2\2\u016a\u016b\7p\2\2\u016b\u016c\7f\2\2\u016c\u016d"+
+        "\7u\2\2\u016dl\3\2\2\2\u016e\u016f\7o\2\2\u016f\u0170\7k\2\2\u0170\u0171"+
+        "\7n\2\2\u0171\u0172\7n\2\2\u0172\u0173\7k\2\2\u0173\u0174\7u\2\2\u0174"+
+        "\u0175\7g\2\2\u0175\u0176\7e\2\2\u0176\u0177\7q\2\2\u0177\u0178\7p\2\2"+
+        "\u0178\u0179\7f\2\2\u0179\u017a\7u\2\2\u017an\3\2\2\2\u017b\u017c\7B\2"+
+        "\2\u017c\u017d\5u;\2\u017dp\3\2\2\2\u017e\u017f\7B\2\2\u017f\u0180\5u"+
+        ";\2\u0180\u0185\7V\2\2\u0181\u0183\5w<\2\u0182\u0184\5y=\2\u0183\u0182"+
+        "\3\2\2\2\u0183\u0184\3\2\2\2\u0184\u0186\3\2\2\2\u0185\u0181\3\2\2\2\u0185"+
+        "\u0186\3\2\2\2\u0186r\3\2\2\2\u0187\u0188\7B\2\2\u0188\u0189\7V\2\2\u0189"+
+        "\u018a\5w<\2\u018at\3\2\2\2\u018b\u018c\t\2\2\2\u018c\u018d\t\2\2\2\u018d"+
+        "\u018e\t\2\2\2\u018e\u0197\t\2\2\2\u018f\u0190\7/\2\2\u0190\u0191\t\2"+
+        "\2\2\u0191\u0195\t\2\2\2\u0192\u0193\7/\2\2\u0193\u0194\t\2\2\2\u0194"+
+        "\u0196\t\2\2\2\u0195\u0192\3\2\2\2\u0195\u0196\3\2\2\2\u0196\u0198\3\2"+
+        "\2\2\u0197\u018f\3\2\2\2\u0197\u0198\3\2\2\2\u0198v\3\2\2\2\u0199\u019a"+
+        "\t\2\2\2\u019a\u01ab\t\2\2\2\u019b\u019c\7<\2\2\u019c\u019d\t\2\2\2\u019d"+
+        "\u01a9\t\2\2\2\u019e\u019f\7<\2\2\u019f\u01a0\t\2\2\2\u01a0\u01a7\t\2"+
+        "\2\2\u01a1\u01a3\7\60\2\2\u01a2\u01a4\t\2\2\2\u01a3\u01a2\3\2\2\2\u01a4"+
+        "\u01a5\3\2\2\2\u01a5\u01a3\3\2\2\2\u01a5\u01a6\3\2\2\2\u01a6\u01a8\3\2"+
+        "\2\2\u01a7\u01a1\3\2\2\2\u01a7\u01a8\3\2\2\2\u01a8\u01aa\3\2\2\2\u01a9"+
+        "\u019e\3\2\2\2\u01a9\u01aa\3\2\2\2\u01aa\u01ac\3\2\2\2\u01ab\u019b\3\2"+
+        "\2\2\u01ab\u01ac\3\2\2\2\u01acx\3\2\2\2\u01ad\u01b5\7\\\2\2\u01ae\u01af"+
+        "\t\3\2\2\u01af\u01b0\t\2\2\2\u01b0\u01b1\t\2\2\2\u01b1\u01b2\7<\2\2\u01b2"+
+        "\u01b3\t\2\2\2\u01b3\u01b5\t\2\2\2\u01b4\u01ad\3\2\2\2\u01b4\u01ae\3\2"+
+        "\2\2\u01b5z\3\2\2\2\u01b6\u01b8\t\4\2\2\u01b7\u01b6\3\2\2\2\u01b8\u01bc"+
+        "\3\2\2\2\u01b9\u01bb\t\5\2\2\u01ba\u01b9\3\2\2\2\u01bb\u01be\3\2\2\2\u01bc"+
+        "\u01ba\3\2\2\2\u01bc\u01bd\3\2\2\2\u01bd|\3\2\2\2\u01be\u01bc\3\2\2\2"+
+        "\u01bf\u01c4\7b\2\2\u01c0\u01c3\5\u0089E\2\u01c1\u01c3\13\2\2\2\u01c2"+
+        "\u01c0\3\2\2\2\u01c2\u01c1\3\2\2\2\u01c3\u01c6\3\2\2\2\u01c4\u01c5\3\2"+
+        "\2\2\u01c4\u01c2\3\2\2\2\u01c5\u01c7\3\2\2\2\u01c6\u01c4\3\2\2\2\u01c7"+
+        "\u01c8\7b\2\2\u01c8~\3\2\2\2\u01c9\u01ce\7)\2\2\u01ca\u01cd\5\u0089E\2"+
+        "\u01cb\u01cd\13\2\2\2\u01cc\u01ca\3\2\2\2\u01cc\u01cb\3\2\2\2\u01cd\u01d0"+
+        "\3\2\2\2\u01ce\u01cf\3\2\2\2\u01ce\u01cc\3\2\2\2\u01cf\u01d1\3\2\2\2\u01d0"+
+        "\u01ce\3\2\2\2\u01d1\u01d2\7)\2\2\u01d2\u0080\3\2\2\2\u01d3\u01d5\t\2"+
+        "\2\2\u01d4\u01d3\3\2\2\2\u01d5\u01d6\3\2\2\2\u01d6\u01d4\3\2\2\2\u01d6"+
+        "\u01d7\3\2\2\2\u01d7\u01de\3\2\2\2\u01d8\u01da\7\60\2\2\u01d9\u01db\t"+
+        "\2\2\2\u01da\u01d9\3\2\2\2\u01db\u01dc\3\2\2\2\u01dc\u01da\3\2\2\2\u01dc"+
+        "\u01dd\3\2\2\2\u01dd\u01df\3\2\2\2\u01de\u01d8\3\2\2\2\u01de\u01df\3\2"+
+        "\2\2\u01df\u0082\3\2\2\2\u01e0\u01e2\t\6\2\2\u01e1\u01e0\3\2\2\2\u01e2"+
+        "\u01e3\3\2\2\2\u01e3\u01e1\3\2\2\2\u01e3\u01e4\3\2\2\2\u01e4\u01e5\3\2"+
+        "\2\2\u01e5\u01e6\bB\2\2\u01e6\u0084\3\2\2\2\u01e7\u01e8\7\61\2\2\u01e8"+
+        "\u01e9\7,\2\2\u01e9\u01ed\3\2\2\2\u01ea\u01ec\13\2\2\2\u01eb\u01ea\3\2"+
+        "\2\2\u01ec\u01ef\3\2\2\2\u01ed\u01ee\3\2\2\2\u01ed\u01eb\3\2\2\2\u01ee"+
+        "\u01f0\3\2\2\2\u01ef\u01ed\3\2\2\2\u01f0\u01f1\7,\2\2\u01f1\u01f2\7\61"+
+        "\2\2\u01f2\u01f3\3\2\2\2\u01f3\u01f4\bC\2\2\u01f4\u0086\3\2\2\2\u01f5"+
+        "\u01f6\7\61\2\2\u01f6\u01f7\7\61\2\2\u01f7\u01fb\3\2\2\2\u01f8\u01fa\n"+
+        "\7\2\2\u01f9\u01f8\3\2\2\2\u01fa\u01fd\3\2\2\2\u01fb\u01f9\3\2\2\2\u01fb"+
+        "\u01fc\3\2\2\2\u01fc\u01fe\3\2\2\2\u01fd\u01fb\3\2\2\2\u01fe\u01ff\bD"+
+        "\2\2\u01ff\u0088\3\2\2\2\u0200\u0203\7^\2\2\u0201\u0204\t\b\2\2\u0202"+
+        "\u0204\5\u008bF\2\u0203\u0201\3\2\2\2\u0203\u0202\3\2\2\2\u0204\u008a"+
+        "\3\2\2\2\u0205\u0206\7w\2\2\u0206\u0207\5\u008dG\2\u0207\u0208\5\u008d"+
+        "G\2\u0208\u0209\5\u008dG\2\u0209\u020a\5\u008dG\2\u020a\u008c\3\2\2\2"+
+        "\u020b\u020c\t\t\2\2\u020c\u008e\3\2\2\2\32\2\u0183\u0185\u0195\u0197"+
+        "\u01a5\u01a7\u01a9\u01ab\u01b4\u01b7\u01ba\u01bc\u01c2\u01c4\u01cc\u01ce"+
+        "\u01d6\u01dc\u01de\u01e3\u01ed\u01fb\u0203\3\2\3\2";
+    public static final ATN _ATN =
+        new ATNDeserializer().deserialize(_serializedATN.toCharArray());
     static {
         _decisionToDFA = new DFA[_ATN.getNumberOfDecisions()];
         for (int i = 0; i < _ATN.getNumberOfDecisions(); i++) {
             _decisionToDFA[i] = new DFA(_ATN.getDecisionState(i), i);
         }
     }
-}
+}
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathLexer.tokens b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathLexer.tokens
index 0fe45617b71..38c5116464f 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathLexer.tokens
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathLexer.tokens
@@ -52,15 +52,16 @@ T__50=51
 T__51=52
 T__52=53
 T__53=54
-DATETIME=55
-TIME=56
-IDENTIFIER=57
-DELIMITEDIDENTIFIER=58
-STRING=59
-NUMBER=60
-WS=61
-COMMENT=62
-LINE_COMMENT=63
+DATE=55
+DATETIME=56
+TIME=57
+IDENTIFIER=58
+DELIMITEDIDENTIFIER=59
+STRING=60
+NUMBER=61
+WS=62
+COMMENT=63
+LINE_COMMENT=64
 '.'=1
 '['=2
 ']'=3
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathNode.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathNode.java
index 7300a273aee..1968684da17 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathNode.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathNode.java
@@ -16,7 +16,7 @@ public interface FHIRPathNode extends Comparable<FHIRPathNode> {
     String path();
     FHIRPathType type();
     boolean hasValue();
-    FHIRPathPrimitiveValue getValue();
+    FHIRPathSystemValue getValue();
     Collection<FHIRPathNode> children();
     Stream<FHIRPathNode> stream();
     Collection<FHIRPathNode> descendants();
@@ -31,7 +31,7 @@ default boolean isElementNode() {
     default boolean isResourceNode() {
         return false;
     }
-    default boolean isPrimitiveValue() {
+    default boolean isSystemValue() {
         return false;
     }
     default boolean isTypeInfoNode() {
@@ -43,8 +43,8 @@ default FHIRPathElementNode asElementNode() {
     default FHIRPathResourceNode asResourceNode() {
         return as(FHIRPathResourceNode.class);
     }
-    default FHIRPathPrimitiveValue asPrimitiveValue() {
-        return as(FHIRPathPrimitiveValue.class);
+    default FHIRPathSystemValue asSystemValue() {
+        return as(FHIRPathSystemValue.class);
     }
     default FHIRPathTypeInfoNode asTypeInfoNode() {
         return as(FHIRPathTypeInfoNode.class);
@@ -52,13 +52,10 @@ default FHIRPathTypeInfoNode asTypeInfoNode() {
     interface Builder { 
         Builder name(String name);
         Builder path(String path);
-        Builder value(FHIRPathPrimitiveValue value);
+        Builder value(FHIRPathSystemValue value);
         Builder children(FHIRPathNode... children);
         Builder children(Collection<FHIRPathNode> children);
         FHIRPathNode build();
     }
-    <T> void accept(T param, FHIRPathNodeVisitor<T> visitor);
-    default <T> void accept(FHIRPathNodeVisitor<T> visitor) {
-        accept(null, visitor);
-    }
+    void accept(FHIRPathNodeVisitor visitor);
 }
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathNumberValue.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathNumberValue.java
index 77706456f04..d055952a272 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathNumberValue.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathNumberValue.java
@@ -8,7 +8,7 @@
 
 import java.math.BigDecimal;
 
-public interface FHIRPathNumberValue extends FHIRPathPrimitiveValue {
+public interface FHIRPathNumberValue extends FHIRPathSystemValue {
     @Override
     default boolean isNumberValue() {
         return true;
@@ -52,10 +52,9 @@ default Number number() {
 
     @Override
     default boolean isComparableTo(FHIRPathNode other) {
-        if (other instanceof FHIRPathQuantityNode) {
-            return ((FHIRPathQuantityNode) other).isComparableTo(this);
-        }
-        return other instanceof FHIRPathNumberValue || 
+        return other instanceof FHIRPathQuantityValue || 
+                other.getValue() instanceof FHIRPathQuantityValue || 
+                other instanceof FHIRPathNumberValue || 
                 other.getValue() instanceof FHIRPathNumberValue;
     }
     
@@ -64,8 +63,11 @@ default int compareTo(FHIRPathNode other) {
         if (!isComparableTo(other)) {
             throw new IllegalArgumentException();
         }
-        if (other instanceof FHIRPathQuantityNode) {
-            return decimal().compareTo(((FHIRPathQuantityNode) other).getQuantityValue());
+        if (other instanceof FHIRPathQuantityValue) {
+            return decimal().compareTo(((FHIRPathQuantityValue) other).value());
+        }
+        if (other.getValue() instanceof FHIRPathQuantityValue) {
+            return decimal().compareTo(((FHIRPathQuantityValue) other.getValue()).value());
         }
         FHIRPathNumberValue value = (FHIRPathNumberValue) ((other instanceof FHIRPathNumberValue) ? other : other.getValue());
         return decimal().compareTo(value.decimal());
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathParser.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathParser.java
index 2ee01385b91..7267a68b5d3 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathParser.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathParser.java
@@ -1,59 +1,69 @@
-/*
- * (C) Copyright IBM Corp. 2019
- *
- * SPDX-License-Identifier: Apache-2.0
- */
-
+// Generated from FHIRPath.g4 by ANTLR 4.7.2
 package com.ibm.fhir.model.path;
-
-import java.util.List;
-
-import org.antlr.v4.runtime.FailedPredicateException;
-import org.antlr.v4.runtime.NoViableAltException;
-import org.antlr.v4.runtime.Parser;
-import org.antlr.v4.runtime.ParserRuleContext;
-import org.antlr.v4.runtime.RecognitionException;
-import org.antlr.v4.runtime.RuleContext;
-import org.antlr.v4.runtime.RuntimeMetaData;
-import org.antlr.v4.runtime.TokenStream;
-import org.antlr.v4.runtime.Vocabulary;
-import org.antlr.v4.runtime.VocabularyImpl;
-import org.antlr.v4.runtime.atn.ATN;
-import org.antlr.v4.runtime.atn.ATNDeserializer;
-import org.antlr.v4.runtime.atn.ParserATNSimulator;
-import org.antlr.v4.runtime.atn.PredictionContextCache;
+import org.antlr.v4.runtime.atn.*;
 import org.antlr.v4.runtime.dfa.DFA;
-import org.antlr.v4.runtime.tree.ParseTreeVisitor;
-import org.antlr.v4.runtime.tree.TerminalNode;
+import org.antlr.v4.runtime.*;
+import org.antlr.v4.runtime.misc.*;
+import org.antlr.v4.runtime.tree.*;
+import java.util.List;
+import java.util.Iterator;
+import java.util.ArrayList;
 
-@SuppressWarnings({ "all", "warnings", "unchecked", "unused", "cast" })
+@SuppressWarnings({"all", "warnings", "unchecked", "unused", "cast"})
 public class FHIRPathParser extends Parser {
-    static {
-        RuntimeMetaData.checkVersion("4.5.3", RuntimeMetaData.VERSION);
-    }
+    static { RuntimeMetaData.checkVersion("4.7.2", RuntimeMetaData.VERSION); }
 
     protected static final DFA[] _decisionToDFA;
-    protected static final PredictionContextCache _sharedContextCache = new PredictionContextCache();
-    public static final int T__0 = 1, T__1 = 2, T__2 = 3, T__3 = 4, T__4 = 5, T__5 = 6, T__6 = 7, T__7 = 8, T__8 = 9, T__9 = 10, T__10 = 11, T__11 = 12,
-            T__12 = 13, T__13 = 14, T__14 = 15, T__15 = 16, T__16 = 17, T__17 = 18, T__18 = 19, T__19 = 20, T__20 = 21, T__21 = 22, T__22 = 23, T__23 = 24,
-            T__24 = 25, T__25 = 26, T__26 = 27, T__27 = 28, T__28 = 29, T__29 = 30, T__30 = 31, T__31 = 32, T__32 = 33, T__33 = 34, T__34 = 35, T__35 = 36,
-            T__36 = 37, T__37 = 38, T__38 = 39, T__39 = 40, T__40 = 41, T__41 = 42, T__42 = 43, T__43 = 44, T__44 = 45, T__45 = 46, T__46 = 47, T__47 = 48,
-            T__48 = 49, T__49 = 50, T__50 = 51, T__51 = 52, T__52 = 53, T__53 = 54, DATETIME = 55, TIME = 56, IDENTIFIER = 57, DELIMITEDIDENTIFIER = 58,
-            STRING = 59, NUMBER = 60, WS = 61, COMMENT = 62, LINE_COMMENT = 63;
-    public static final int RULE_expression = 0, RULE_term = 1, RULE_literal = 2, RULE_externalConstant = 3, RULE_invocation = 4, RULE_function = 5,
-            RULE_paramList = 6, RULE_quantity = 7, RULE_unit = 8, RULE_dateTimePrecision = 9, RULE_pluralDateTimePrecision = 10, RULE_typeSpecifier = 11,
-            RULE_qualifiedIdentifier = 12, RULE_identifier = 13;
-    public static final String[] ruleNames = { "expression", "term", "literal", "externalConstant", "invocation", "function", "paramList", "quantity", "unit",
-            "dateTimePrecision", "pluralDateTimePrecision", "typeSpecifier", "qualifiedIdentifier", "identifier" };
-
-    private static final String[] _LITERAL_NAMES = { null, "'.'", "'['", "']'", "'+'", "'-'", "'*'", "'/'", "'div'", "'mod'", "'&'", "'is'", "'as'", "'|'",
-            "'<='", "'<'", "'>'", "'>='", "'='", "'~'", "'!='", "'!~'", "'in'", "'contains'", "'and'", "'or'", "'xor'", "'implies'", "'('", "')'", "'{'", "'}'",
-            "'true'", "'false'", "'%'", "'$this'", "'$index'", "'$total'", "','", "'year'", "'month'", "'week'", "'day'", "'hour'", "'minute'", "'second'",
-            "'millisecond'", "'years'", "'months'", "'weeks'", "'days'", "'hours'", "'minutes'", "'seconds'", "'milliseconds'" };
-    private static final String[] _SYMBOLIC_NAMES = { null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null,
-            null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null,
-            null, null, null, null, null, null, null, null, null, null, null, null, null, null, "DATETIME", "TIME", "IDENTIFIER", "DELIMITEDIDENTIFIER",
-            "STRING", "NUMBER", "WS", "COMMENT", "LINE_COMMENT" };
+    protected static final PredictionContextCache _sharedContextCache =
+        new PredictionContextCache();
+    public static final int
+        T__0=1, T__1=2, T__2=3, T__3=4, T__4=5, T__5=6, T__6=7, T__7=8, T__8=9, 
+        T__9=10, T__10=11, T__11=12, T__12=13, T__13=14, T__14=15, T__15=16, T__16=17, 
+        T__17=18, T__18=19, T__19=20, T__20=21, T__21=22, T__22=23, T__23=24, 
+        T__24=25, T__25=26, T__26=27, T__27=28, T__28=29, T__29=30, T__30=31, 
+        T__31=32, T__32=33, T__33=34, T__34=35, T__35=36, T__36=37, T__37=38, 
+        T__38=39, T__39=40, T__40=41, T__41=42, T__42=43, T__43=44, T__44=45, 
+        T__45=46, T__46=47, T__47=48, T__48=49, T__49=50, T__50=51, T__51=52, 
+        T__52=53, T__53=54, DATE=55, DATETIME=56, TIME=57, IDENTIFIER=58, DELIMITEDIDENTIFIER=59, 
+        STRING=60, NUMBER=61, WS=62, COMMENT=63, LINE_COMMENT=64;
+    public static final int
+        RULE_expression = 0, RULE_term = 1, RULE_literal = 2, RULE_externalConstant = 3, 
+        RULE_invocation = 4, RULE_function = 5, RULE_paramList = 6, RULE_quantity = 7, 
+        RULE_unit = 8, RULE_dateTimePrecision = 9, RULE_pluralDateTimePrecision = 10, 
+        RULE_typeSpecifier = 11, RULE_qualifiedIdentifier = 12, RULE_identifier = 13;
+    private static String[] makeRuleNames() {
+        return new String[] {
+            "expression", "term", "literal", "externalConstant", "invocation", "function", 
+            "paramList", "quantity", "unit", "dateTimePrecision", "pluralDateTimePrecision", 
+            "typeSpecifier", "qualifiedIdentifier", "identifier"
+        };
+    }
+    public static final String[] ruleNames = makeRuleNames();
+
+    private static String[] makeLiteralNames() {
+        return new String[] {
+            null, "'.'", "'['", "']'", "'+'", "'-'", "'*'", "'/'", "'div'", "'mod'", 
+            "'&'", "'is'", "'as'", "'|'", "'<='", "'<'", "'>'", "'>='", "'='", "'~'", 
+            "'!='", "'!~'", "'in'", "'contains'", "'and'", "'or'", "'xor'", "'implies'", 
+            "'('", "')'", "'{'", "'}'", "'true'", "'false'", "'%'", "'$this'", "'$index'", 
+            "'$total'", "','", "'year'", "'month'", "'week'", "'day'", "'hour'", 
+            "'minute'", "'second'", "'millisecond'", "'years'", "'months'", "'weeks'", 
+            "'days'", "'hours'", "'minutes'", "'seconds'", "'milliseconds'"
+        };
+    }
+    private static final String[] _LITERAL_NAMES = makeLiteralNames();
+    private static String[] makeSymbolicNames() {
+        return new String[] {
+            null, null, null, null, null, null, null, null, null, null, null, null, 
+            null, null, null, null, null, null, null, null, null, null, null, null, 
+            null, null, null, null, null, null, null, null, null, null, null, null, 
+            null, null, null, null, null, null, null, null, null, null, null, null, 
+            null, null, null, null, null, null, null, "DATE", "DATETIME", "TIME", 
+            "IDENTIFIER", "DELIMITEDIDENTIFIER", "STRING", "NUMBER", "WS", "COMMENT", 
+            "LINE_COMMENT"
+        };
+    }
+    private static final String[] _SYMBOLIC_NAMES = makeSymbolicNames();
     public static final Vocabulary VOCABULARY = new VocabularyImpl(_LITERAL_NAMES, _SYMBOLIC_NAMES);
 
     /**
@@ -88,345 +98,221 @@ public Vocabulary getVocabulary() {
     }
 
     @Override
-    public String getGrammarFileName() {
-        return "FHIRPath.g4";
-    }
+    public String getGrammarFileName() { return "FHIRPath.g4"; }
 
     @Override
-    public String[] getRuleNames() {
-        return ruleNames;
-    }
+    public String[] getRuleNames() { return ruleNames; }
 
     @Override
-    public String getSerializedATN() {
-        return _serializedATN;
-    }
+    public String getSerializedATN() { return _serializedATN; }
 
     @Override
-    public ATN getATN() {
-        return _ATN;
-    }
+    public ATN getATN() { return _ATN; }
 
     public FHIRPathParser(TokenStream input) {
         super(input);
-        _interp = new ParserATNSimulator(this, _ATN, _decisionToDFA, _sharedContextCache);
+        _interp = new ParserATNSimulator(this,_ATN,_decisionToDFA,_sharedContextCache);
     }
 
     public static class ExpressionContext extends ParserRuleContext {
         public ExpressionContext(ParserRuleContext parent, int invokingState) {
             super(parent, invokingState);
         }
-
-        @Override
-        public int getRuleIndex() {
-            return RULE_expression;
-        }
-
-        public ExpressionContext() {
-        }
-
+        @Override public int getRuleIndex() { return RULE_expression; }
+     
+        public ExpressionContext() { }
         public void copyFrom(ExpressionContext ctx) {
             super.copyFrom(ctx);
         }
     }
-
     public static class IndexerExpressionContext extends ExpressionContext {
         public List<ExpressionContext> expression() {
             return getRuleContexts(ExpressionContext.class);
         }
-
         public ExpressionContext expression(int i) {
-            return getRuleContext(ExpressionContext.class, i);
-        }
-
-        public IndexerExpressionContext(ExpressionContext ctx) {
-            copyFrom(ctx);
+            return getRuleContext(ExpressionContext.class,i);
         }
-
+        public IndexerExpressionContext(ExpressionContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitIndexerExpression(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitIndexerExpression(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class PolarityExpressionContext extends ExpressionContext {
         public ExpressionContext expression() {
-            return getRuleContext(ExpressionContext.class, 0);
-        }
-
-        public PolarityExpressionContext(ExpressionContext ctx) {
-            copyFrom(ctx);
+            return getRuleContext(ExpressionContext.class,0);
         }
-
+        public PolarityExpressionContext(ExpressionContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitPolarityExpression(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitPolarityExpression(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class AdditiveExpressionContext extends ExpressionContext {
         public List<ExpressionContext> expression() {
             return getRuleContexts(ExpressionContext.class);
         }
-
         public ExpressionContext expression(int i) {
-            return getRuleContext(ExpressionContext.class, i);
-        }
-
-        public AdditiveExpressionContext(ExpressionContext ctx) {
-            copyFrom(ctx);
+            return getRuleContext(ExpressionContext.class,i);
         }
-
+        public AdditiveExpressionContext(ExpressionContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitAdditiveExpression(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitAdditiveExpression(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class MultiplicativeExpressionContext extends ExpressionContext {
         public List<ExpressionContext> expression() {
             return getRuleContexts(ExpressionContext.class);
         }
-
         public ExpressionContext expression(int i) {
-            return getRuleContext(ExpressionContext.class, i);
+            return getRuleContext(ExpressionContext.class,i);
         }
-
-        public MultiplicativeExpressionContext(ExpressionContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public MultiplicativeExpressionContext(ExpressionContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitMultiplicativeExpression(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitMultiplicativeExpression(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class UnionExpressionContext extends ExpressionContext {
         public List<ExpressionContext> expression() {
             return getRuleContexts(ExpressionContext.class);
         }
-
         public ExpressionContext expression(int i) {
-            return getRuleContext(ExpressionContext.class, i);
-        }
-
-        public UnionExpressionContext(ExpressionContext ctx) {
-            copyFrom(ctx);
+            return getRuleContext(ExpressionContext.class,i);
         }
-
+        public UnionExpressionContext(ExpressionContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitUnionExpression(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitUnionExpression(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class OrExpressionContext extends ExpressionContext {
         public List<ExpressionContext> expression() {
             return getRuleContexts(ExpressionContext.class);
         }
-
         public ExpressionContext expression(int i) {
-            return getRuleContext(ExpressionContext.class, i);
-        }
-
-        public OrExpressionContext(ExpressionContext ctx) {
-            copyFrom(ctx);
+            return getRuleContext(ExpressionContext.class,i);
         }
-
+        public OrExpressionContext(ExpressionContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitOrExpression(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitOrExpression(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class AndExpressionContext extends ExpressionContext {
         public List<ExpressionContext> expression() {
             return getRuleContexts(ExpressionContext.class);
         }
-
         public ExpressionContext expression(int i) {
-            return getRuleContext(ExpressionContext.class, i);
+            return getRuleContext(ExpressionContext.class,i);
         }
-
-        public AndExpressionContext(ExpressionContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public AndExpressionContext(ExpressionContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitAndExpression(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitAndExpression(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class MembershipExpressionContext extends ExpressionContext {
         public List<ExpressionContext> expression() {
             return getRuleContexts(ExpressionContext.class);
         }
-
         public ExpressionContext expression(int i) {
-            return getRuleContext(ExpressionContext.class, i);
-        }
-
-        public MembershipExpressionContext(ExpressionContext ctx) {
-            copyFrom(ctx);
+            return getRuleContext(ExpressionContext.class,i);
         }
-
+        public MembershipExpressionContext(ExpressionContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitMembershipExpression(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitMembershipExpression(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class InequalityExpressionContext extends ExpressionContext {
         public List<ExpressionContext> expression() {
             return getRuleContexts(ExpressionContext.class);
         }
-
         public ExpressionContext expression(int i) {
-            return getRuleContext(ExpressionContext.class, i);
+            return getRuleContext(ExpressionContext.class,i);
         }
-
-        public InequalityExpressionContext(ExpressionContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public InequalityExpressionContext(ExpressionContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitInequalityExpression(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitInequalityExpression(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class InvocationExpressionContext extends ExpressionContext {
         public ExpressionContext expression() {
-            return getRuleContext(ExpressionContext.class, 0);
+            return getRuleContext(ExpressionContext.class,0);
         }
-
         public InvocationContext invocation() {
-            return getRuleContext(InvocationContext.class, 0);
+            return getRuleContext(InvocationContext.class,0);
         }
-
-        public InvocationExpressionContext(ExpressionContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public InvocationExpressionContext(ExpressionContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitInvocationExpression(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitInvocationExpression(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class EqualityExpressionContext extends ExpressionContext {
         public List<ExpressionContext> expression() {
             return getRuleContexts(ExpressionContext.class);
         }
-
         public ExpressionContext expression(int i) {
-            return getRuleContext(ExpressionContext.class, i);
-        }
-
-        public EqualityExpressionContext(ExpressionContext ctx) {
-            copyFrom(ctx);
+            return getRuleContext(ExpressionContext.class,i);
         }
-
+        public EqualityExpressionContext(ExpressionContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitEqualityExpression(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitEqualityExpression(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class ImpliesExpressionContext extends ExpressionContext {
         public List<ExpressionContext> expression() {
             return getRuleContexts(ExpressionContext.class);
         }
-
         public ExpressionContext expression(int i) {
-            return getRuleContext(ExpressionContext.class, i);
-        }
-
-        public ImpliesExpressionContext(ExpressionContext ctx) {
-            copyFrom(ctx);
+            return getRuleContext(ExpressionContext.class,i);
         }
-
+        public ImpliesExpressionContext(ExpressionContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitImpliesExpression(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitImpliesExpression(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class TermExpressionContext extends ExpressionContext {
         public TermContext term() {
-            return getRuleContext(TermContext.class, 0);
-        }
-
-        public TermExpressionContext(ExpressionContext ctx) {
-            copyFrom(ctx);
+            return getRuleContext(TermContext.class,0);
         }
-
+        public TermExpressionContext(ExpressionContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitTermExpression(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitTermExpression(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class TypeExpressionContext extends ExpressionContext {
         public ExpressionContext expression() {
-            return getRuleContext(ExpressionContext.class, 0);
+            return getRuleContext(ExpressionContext.class,0);
         }
-
         public TypeSpecifierContext typeSpecifier() {
-            return getRuleContext(TypeSpecifierContext.class, 0);
+            return getRuleContext(TypeSpecifierContext.class,0);
         }
-
-        public TypeExpressionContext(ExpressionContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public TypeExpressionContext(ExpressionContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitTypeExpression(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitTypeExpression(this);
+            else return visitor.visitChildren(this);
         }
     }
 
@@ -446,258 +332,289 @@ private ExpressionContext expression(int _p) throws RecognitionException {
             int _alt;
             enterOuterAlt(_localctx, 1);
             {
-                setState(32);
-                switch (_input.LA(1)) {
-                case T__10:
-                case T__11:
-                case T__27:
-                case T__29:
-                case T__31:
-                case T__32:
-                case T__33:
-                case T__34:
-                case T__35:
-                case T__36:
-                case DATETIME:
-                case TIME:
-                case IDENTIFIER:
-                case DELIMITEDIDENTIFIER:
-                case STRING:
-                case NUMBER: {
-                    _localctx = new TermExpressionContext(_localctx);
-                    _ctx = _localctx;
-                    _prevctx = _localctx;
+            setState(32);
+            _errHandler.sync(this);
+            switch (_input.LA(1)) {
+            case T__10:
+            case T__11:
+            case T__21:
+            case T__22:
+            case T__27:
+            case T__29:
+            case T__31:
+            case T__32:
+            case T__33:
+            case T__34:
+            case T__35:
+            case T__36:
+            case DATE:
+            case DATETIME:
+            case TIME:
+            case IDENTIFIER:
+            case DELIMITEDIDENTIFIER:
+            case STRING:
+            case NUMBER:
+                {
+                _localctx = new TermExpressionContext(_localctx);
+                _ctx = _localctx;
+                _prevctx = _localctx;
 
-                    setState(29);
-                    term();
+                setState(29);
+                term();
                 }
-                    break;
-                case T__3:
-                case T__4: {
-                    _localctx = new PolarityExpressionContext(_localctx);
-                    _ctx = _localctx;
-                    _prevctx = _localctx;
-                    setState(30);
-                    _la = _input.LA(1);
-                    if (!(_la == T__3 || _la == T__4)) {
-                        _errHandler.recoverInline(this);
-                    } else {
-                        consume();
-                    }
-                    setState(31);
-                    expression(11);
+                break;
+            case T__3:
+            case T__4:
+                {
+                _localctx = new PolarityExpressionContext(_localctx);
+                _ctx = _localctx;
+                _prevctx = _localctx;
+                setState(30);
+                _la = _input.LA(1);
+                if ( !(_la==T__3 || _la==T__4) ) {
+                _errHandler.recoverInline(this);
                 }
-                    break;
-                default:
-                    throw new NoViableAltException(this);
+                else {
+                    if ( _input.LA(1)==Token.EOF ) matchedEOF = true;
+                    _errHandler.reportMatch(this);
+                    consume();
                 }
-                _ctx.stop = _input.LT(-1);
-                setState(74);
-                _errHandler.sync(this);
-                _alt = getInterpreter().adaptivePredict(_input, 2, _ctx);
-                while (_alt != 2 && _alt != org.antlr.v4.runtime.atn.ATN.INVALID_ALT_NUMBER) {
-                    if (_alt == 1) {
-                        if (_parseListeners != null)
-                            triggerExitRuleEvent();
-                        _prevctx = _localctx;
+                setState(31);
+                expression(11);
+                }
+                break;
+            default:
+                throw new NoViableAltException(this);
+            }
+            _ctx.stop = _input.LT(-1);
+            setState(74);
+            _errHandler.sync(this);
+            _alt = getInterpreter().adaptivePredict(_input,2,_ctx);
+            while ( _alt!=2 && _alt!=org.antlr.v4.runtime.atn.ATN.INVALID_ALT_NUMBER ) {
+                if ( _alt==1 ) {
+                    if ( _parseListeners!=null ) triggerExitRuleEvent();
+                    _prevctx = _localctx;
+                    {
+                    setState(72);
+                    _errHandler.sync(this);
+                    switch ( getInterpreter().adaptivePredict(_input,1,_ctx) ) {
+                    case 1:
+                        {
+                        _localctx = new MultiplicativeExpressionContext(new ExpressionContext(_parentctx, _parentState));
+                        pushNewRecursionContext(_localctx, _startState, RULE_expression);
+                        setState(34);
+                        if (!(precpred(_ctx, 10))) throw new FailedPredicateException(this, "precpred(_ctx, 10)");
+                        setState(35);
+                        _la = _input.LA(1);
+                        if ( !((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__5) | (1L << T__6) | (1L << T__7) | (1L << T__8))) != 0)) ) {
+                        _errHandler.recoverInline(this);
+                        }
+                        else {
+                            if ( _input.LA(1)==Token.EOF ) matchedEOF = true;
+                            _errHandler.reportMatch(this);
+                            consume();
+                        }
+                        setState(36);
+                        expression(11);
+                        }
+                        break;
+                    case 2:
+                        {
+                        _localctx = new AdditiveExpressionContext(new ExpressionContext(_parentctx, _parentState));
+                        pushNewRecursionContext(_localctx, _startState, RULE_expression);
+                        setState(37);
+                        if (!(precpred(_ctx, 9))) throw new FailedPredicateException(this, "precpred(_ctx, 9)");
+                        setState(38);
+                        _la = _input.LA(1);
+                        if ( !((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__3) | (1L << T__4) | (1L << T__9))) != 0)) ) {
+                        _errHandler.recoverInline(this);
+                        }
+                        else {
+                            if ( _input.LA(1)==Token.EOF ) matchedEOF = true;
+                            _errHandler.reportMatch(this);
+                            consume();
+                        }
+                        setState(39);
+                        expression(10);
+                        }
+                        break;
+                    case 3:
+                        {
+                        _localctx = new UnionExpressionContext(new ExpressionContext(_parentctx, _parentState));
+                        pushNewRecursionContext(_localctx, _startState, RULE_expression);
+                        setState(40);
+                        if (!(precpred(_ctx, 7))) throw new FailedPredicateException(this, "precpred(_ctx, 7)");
+                        setState(41);
+                        match(T__12);
+                        setState(42);
+                        expression(8);
+                        }
+                        break;
+                    case 4:
+                        {
+                        _localctx = new InequalityExpressionContext(new ExpressionContext(_parentctx, _parentState));
+                        pushNewRecursionContext(_localctx, _startState, RULE_expression);
+                        setState(43);
+                        if (!(precpred(_ctx, 6))) throw new FailedPredicateException(this, "precpred(_ctx, 6)");
+                        setState(44);
+                        _la = _input.LA(1);
+                        if ( !((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__13) | (1L << T__14) | (1L << T__15) | (1L << T__16))) != 0)) ) {
+                        _errHandler.recoverInline(this);
+                        }
+                        else {
+                            if ( _input.LA(1)==Token.EOF ) matchedEOF = true;
+                            _errHandler.reportMatch(this);
+                            consume();
+                        }
+                        setState(45);
+                        expression(7);
+                        }
+                        break;
+                    case 5:
                         {
-                            setState(72);
-                            _errHandler.sync(this);
-                            switch (getInterpreter().adaptivePredict(_input, 1, _ctx)) {
-                            case 1: {
-                                _localctx = new MultiplicativeExpressionContext(new ExpressionContext(_parentctx, _parentState));
-                                pushNewRecursionContext(_localctx, _startState, RULE_expression);
-                                setState(34);
-                                if (!(precpred(_ctx, 10)))
-                                    throw new FailedPredicateException(this, "precpred(_ctx, 10)");
-                                setState(35);
-                                _la = _input.LA(1);
-                                if (!((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__5) | (1L << T__6) | (1L << T__7) | (1L << T__8))) != 0))) {
-                                    _errHandler.recoverInline(this);
-                                } else {
-                                    consume();
-                                }
-                                setState(36);
-                                expression(11);
-                            }
-                                break;
-                            case 2: {
-                                _localctx = new AdditiveExpressionContext(new ExpressionContext(_parentctx, _parentState));
-                                pushNewRecursionContext(_localctx, _startState, RULE_expression);
-                                setState(37);
-                                if (!(precpred(_ctx, 9)))
-                                    throw new FailedPredicateException(this, "precpred(_ctx, 9)");
-                                setState(38);
-                                _la = _input.LA(1);
-                                if (!((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__3) | (1L << T__4) | (1L << T__9))) != 0))) {
-                                    _errHandler.recoverInline(this);
-                                } else {
-                                    consume();
-                                }
-                                setState(39);
-                                expression(10);
-                            }
-                                break;
-                            case 3: {
-                                _localctx = new UnionExpressionContext(new ExpressionContext(_parentctx, _parentState));
-                                pushNewRecursionContext(_localctx, _startState, RULE_expression);
-                                setState(40);
-                                if (!(precpred(_ctx, 7)))
-                                    throw new FailedPredicateException(this, "precpred(_ctx, 7)");
-                                setState(41);
-                                match(T__12);
-                                setState(42);
-                                expression(8);
-                            }
-                                break;
-                            case 4: {
-                                _localctx = new InequalityExpressionContext(new ExpressionContext(_parentctx, _parentState));
-                                pushNewRecursionContext(_localctx, _startState, RULE_expression);
-                                setState(43);
-                                if (!(precpred(_ctx, 6)))
-                                    throw new FailedPredicateException(this, "precpred(_ctx, 6)");
-                                setState(44);
-                                _la = _input.LA(1);
-                                if (!((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__13) | (1L << T__14) | (1L << T__15) | (1L << T__16))) != 0))) {
-                                    _errHandler.recoverInline(this);
-                                } else {
-                                    consume();
-                                }
-                                setState(45);
-                                expression(7);
-                            }
-                                break;
-                            case 5: {
-                                _localctx = new EqualityExpressionContext(new ExpressionContext(_parentctx, _parentState));
-                                pushNewRecursionContext(_localctx, _startState, RULE_expression);
-                                setState(46);
-                                if (!(precpred(_ctx, 5)))
-                                    throw new FailedPredicateException(this, "precpred(_ctx, 5)");
-                                setState(47);
-                                _la = _input.LA(1);
-                                if (!((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__17) | (1L << T__18) | (1L << T__19) | (1L << T__20))) != 0))) {
-                                    _errHandler.recoverInline(this);
-                                } else {
-                                    consume();
-                                }
-                                setState(48);
-                                expression(6);
-                            }
-                                break;
-                            case 6: {
-                                _localctx = new MembershipExpressionContext(new ExpressionContext(_parentctx, _parentState));
-                                pushNewRecursionContext(_localctx, _startState, RULE_expression);
-                                setState(49);
-                                if (!(precpred(_ctx, 4)))
-                                    throw new FailedPredicateException(this, "precpred(_ctx, 4)");
-                                setState(50);
-                                _la = _input.LA(1);
-                                if (!(_la == T__21 || _la == T__22)) {
-                                    _errHandler.recoverInline(this);
-                                } else {
-                                    consume();
-                                }
-                                setState(51);
-                                expression(5);
-                            }
-                                break;
-                            case 7: {
-                                _localctx = new AndExpressionContext(new ExpressionContext(_parentctx, _parentState));
-                                pushNewRecursionContext(_localctx, _startState, RULE_expression);
-                                setState(52);
-                                if (!(precpred(_ctx, 3)))
-                                    throw new FailedPredicateException(this, "precpred(_ctx, 3)");
-                                setState(53);
-                                match(T__23);
-                                setState(54);
-                                expression(4);
-                            }
-                                break;
-                            case 8: {
-                                _localctx = new OrExpressionContext(new ExpressionContext(_parentctx, _parentState));
-                                pushNewRecursionContext(_localctx, _startState, RULE_expression);
-                                setState(55);
-                                if (!(precpred(_ctx, 2)))
-                                    throw new FailedPredicateException(this, "precpred(_ctx, 2)");
-                                setState(56);
-                                _la = _input.LA(1);
-                                if (!(_la == T__24 || _la == T__25)) {
-                                    _errHandler.recoverInline(this);
-                                } else {
-                                    consume();
-                                }
-                                setState(57);
-                                expression(3);
-                            }
-                                break;
-                            case 9: {
-                                _localctx = new ImpliesExpressionContext(new ExpressionContext(_parentctx, _parentState));
-                                pushNewRecursionContext(_localctx, _startState, RULE_expression);
-                                setState(58);
-                                if (!(precpred(_ctx, 1)))
-                                    throw new FailedPredicateException(this, "precpred(_ctx, 1)");
-                                setState(59);
-                                match(T__26);
-                                setState(60);
-                                expression(2);
-                            }
-                                break;
-                            case 10: {
-                                _localctx = new InvocationExpressionContext(new ExpressionContext(_parentctx, _parentState));
-                                pushNewRecursionContext(_localctx, _startState, RULE_expression);
-                                setState(61);
-                                if (!(precpred(_ctx, 13)))
-                                    throw new FailedPredicateException(this, "precpred(_ctx, 13)");
-                                setState(62);
-                                match(T__0);
-                                setState(63);
-                                invocation();
-                            }
-                                break;
-                            case 11: {
-                                _localctx = new IndexerExpressionContext(new ExpressionContext(_parentctx, _parentState));
-                                pushNewRecursionContext(_localctx, _startState, RULE_expression);
-                                setState(64);
-                                if (!(precpred(_ctx, 12)))
-                                    throw new FailedPredicateException(this, "precpred(_ctx, 12)");
-                                setState(65);
-                                match(T__1);
-                                setState(66);
-                                expression(0);
-                                setState(67);
-                                match(T__2);
-                            }
-                                break;
-                            case 12: {
-                                _localctx = new TypeExpressionContext(new ExpressionContext(_parentctx, _parentState));
-                                pushNewRecursionContext(_localctx, _startState, RULE_expression);
-                                setState(69);
-                                if (!(precpred(_ctx, 8)))
-                                    throw new FailedPredicateException(this, "precpred(_ctx, 8)");
-                                setState(70);
-                                _la = _input.LA(1);
-                                if (!(_la == T__10 || _la == T__11)) {
-                                    _errHandler.recoverInline(this);
-                                } else {
-                                    consume();
-                                }
-                                setState(71);
-                                typeSpecifier();
-                            }
-                                break;
-                            }
+                        _localctx = new EqualityExpressionContext(new ExpressionContext(_parentctx, _parentState));
+                        pushNewRecursionContext(_localctx, _startState, RULE_expression);
+                        setState(46);
+                        if (!(precpred(_ctx, 5))) throw new FailedPredicateException(this, "precpred(_ctx, 5)");
+                        setState(47);
+                        _la = _input.LA(1);
+                        if ( !((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__17) | (1L << T__18) | (1L << T__19) | (1L << T__20))) != 0)) ) {
+                        _errHandler.recoverInline(this);
+                        }
+                        else {
+                            if ( _input.LA(1)==Token.EOF ) matchedEOF = true;
+                            _errHandler.reportMatch(this);
+                            consume();
                         }
+                        setState(48);
+                        expression(6);
+                        }
+                        break;
+                    case 6:
+                        {
+                        _localctx = new MembershipExpressionContext(new ExpressionContext(_parentctx, _parentState));
+                        pushNewRecursionContext(_localctx, _startState, RULE_expression);
+                        setState(49);
+                        if (!(precpred(_ctx, 4))) throw new FailedPredicateException(this, "precpred(_ctx, 4)");
+                        setState(50);
+                        _la = _input.LA(1);
+                        if ( !(_la==T__21 || _la==T__22) ) {
+                        _errHandler.recoverInline(this);
+                        }
+                        else {
+                            if ( _input.LA(1)==Token.EOF ) matchedEOF = true;
+                            _errHandler.reportMatch(this);
+                            consume();
+                        }
+                        setState(51);
+                        expression(5);
+                        }
+                        break;
+                    case 7:
+                        {
+                        _localctx = new AndExpressionContext(new ExpressionContext(_parentctx, _parentState));
+                        pushNewRecursionContext(_localctx, _startState, RULE_expression);
+                        setState(52);
+                        if (!(precpred(_ctx, 3))) throw new FailedPredicateException(this, "precpred(_ctx, 3)");
+                        setState(53);
+                        match(T__23);
+                        setState(54);
+                        expression(4);
+                        }
+                        break;
+                    case 8:
+                        {
+                        _localctx = new OrExpressionContext(new ExpressionContext(_parentctx, _parentState));
+                        pushNewRecursionContext(_localctx, _startState, RULE_expression);
+                        setState(55);
+                        if (!(precpred(_ctx, 2))) throw new FailedPredicateException(this, "precpred(_ctx, 2)");
+                        setState(56);
+                        _la = _input.LA(1);
+                        if ( !(_la==T__24 || _la==T__25) ) {
+                        _errHandler.recoverInline(this);
+                        }
+                        else {
+                            if ( _input.LA(1)==Token.EOF ) matchedEOF = true;
+                            _errHandler.reportMatch(this);
+                            consume();
+                        }
+                        setState(57);
+                        expression(3);
+                        }
+                        break;
+                    case 9:
+                        {
+                        _localctx = new ImpliesExpressionContext(new ExpressionContext(_parentctx, _parentState));
+                        pushNewRecursionContext(_localctx, _startState, RULE_expression);
+                        setState(58);
+                        if (!(precpred(_ctx, 1))) throw new FailedPredicateException(this, "precpred(_ctx, 1)");
+                        setState(59);
+                        match(T__26);
+                        setState(60);
+                        expression(2);
+                        }
+                        break;
+                    case 10:
+                        {
+                        _localctx = new InvocationExpressionContext(new ExpressionContext(_parentctx, _parentState));
+                        pushNewRecursionContext(_localctx, _startState, RULE_expression);
+                        setState(61);
+                        if (!(precpred(_ctx, 13))) throw new FailedPredicateException(this, "precpred(_ctx, 13)");
+                        setState(62);
+                        match(T__0);
+                        setState(63);
+                        invocation();
+                        }
+                        break;
+                    case 11:
+                        {
+                        _localctx = new IndexerExpressionContext(new ExpressionContext(_parentctx, _parentState));
+                        pushNewRecursionContext(_localctx, _startState, RULE_expression);
+                        setState(64);
+                        if (!(precpred(_ctx, 12))) throw new FailedPredicateException(this, "precpred(_ctx, 12)");
+                        setState(65);
+                        match(T__1);
+                        setState(66);
+                        expression(0);
+                        setState(67);
+                        match(T__2);
+                        }
+                        break;
+                    case 12:
+                        {
+                        _localctx = new TypeExpressionContext(new ExpressionContext(_parentctx, _parentState));
+                        pushNewRecursionContext(_localctx, _startState, RULE_expression);
+                        setState(69);
+                        if (!(precpred(_ctx, 8))) throw new FailedPredicateException(this, "precpred(_ctx, 8)");
+                        setState(70);
+                        _la = _input.LA(1);
+                        if ( !(_la==T__10 || _la==T__11) ) {
+                        _errHandler.recoverInline(this);
+                        }
+                        else {
+                            if ( _input.LA(1)==Token.EOF ) matchedEOF = true;
+                            _errHandler.reportMatch(this);
+                            consume();
+                        }
+                        setState(71);
+                        typeSpecifier();
+                        }
+                        break;
                     }
-                    setState(76);
-                    _errHandler.sync(this);
-                    _alt = getInterpreter().adaptivePredict(_input, 2, _ctx);
+                    } 
                 }
+                setState(76);
+                _errHandler.sync(this);
+                _alt = getInterpreter().adaptivePredict(_input,2,_ctx);
             }
-        } catch (RecognitionException re) {
+            }
+        }
+        catch (RecognitionException re) {
             _localctx.exception = re;
             _errHandler.reportError(this, re);
             _errHandler.recover(this, re);
-        } finally {
+        }
+        finally {
             unrollRecursionContexts(_parentctx);
         }
         return _localctx;
@@ -707,89 +624,55 @@ public static class TermContext extends ParserRuleContext {
         public TermContext(ParserRuleContext parent, int invokingState) {
             super(parent, invokingState);
         }
-
-        @Override
-        public int getRuleIndex() {
-            return RULE_term;
-        }
-
-        public TermContext() {
-        }
-
+        @Override public int getRuleIndex() { return RULE_term; }
+     
+        public TermContext() { }
         public void copyFrom(TermContext ctx) {
             super.copyFrom(ctx);
         }
     }
-
     public static class ExternalConstantTermContext extends TermContext {
         public ExternalConstantContext externalConstant() {
-            return getRuleContext(ExternalConstantContext.class, 0);
-        }
-
-        public ExternalConstantTermContext(TermContext ctx) {
-            copyFrom(ctx);
+            return getRuleContext(ExternalConstantContext.class,0);
         }
-
+        public ExternalConstantTermContext(TermContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitExternalConstantTerm(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitExternalConstantTerm(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class LiteralTermContext extends TermContext {
         public LiteralContext literal() {
-            return getRuleContext(LiteralContext.class, 0);
-        }
-
-        public LiteralTermContext(TermContext ctx) {
-            copyFrom(ctx);
+            return getRuleContext(LiteralContext.class,0);
         }
-
+        public LiteralTermContext(TermContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitLiteralTerm(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitLiteralTerm(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class ParenthesizedTermContext extends TermContext {
         public ExpressionContext expression() {
-            return getRuleContext(ExpressionContext.class, 0);
-        }
-
-        public ParenthesizedTermContext(TermContext ctx) {
-            copyFrom(ctx);
+            return getRuleContext(ExpressionContext.class,0);
         }
-
+        public ParenthesizedTermContext(TermContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitParenthesizedTerm(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitParenthesizedTerm(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class InvocationTermContext extends TermContext {
         public InvocationContext invocation() {
-            return getRuleContext(InvocationContext.class, 0);
-        }
-
-        public InvocationTermContext(TermContext ctx) {
-            copyFrom(ctx);
+            return getRuleContext(InvocationContext.class,0);
         }
-
+        public InvocationTermContext(TermContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitInvocationTerm(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitInvocationTerm(this);
+            else return visitor.visitChildren(this);
         }
     }
 
@@ -798,59 +681,69 @@ public final TermContext term() throws RecognitionException {
         enterRule(_localctx, 2, RULE_term);
         try {
             setState(84);
+            _errHandler.sync(this);
             switch (_input.LA(1)) {
             case T__10:
             case T__11:
+            case T__21:
+            case T__22:
             case T__34:
             case T__35:
             case T__36:
             case IDENTIFIER:
             case DELIMITEDIDENTIFIER:
                 _localctx = new InvocationTermContext(_localctx);
-                enterOuterAlt(_localctx, 1); {
+                enterOuterAlt(_localctx, 1);
+                {
                 setState(77);
                 invocation();
-            }
+                }
                 break;
             case T__29:
             case T__31:
             case T__32:
+            case DATE:
             case DATETIME:
             case TIME:
             case STRING:
             case NUMBER:
                 _localctx = new LiteralTermContext(_localctx);
-                enterOuterAlt(_localctx, 2); {
+                enterOuterAlt(_localctx, 2);
+                {
                 setState(78);
                 literal();
-            }
+                }
                 break;
             case T__33:
                 _localctx = new ExternalConstantTermContext(_localctx);
-                enterOuterAlt(_localctx, 3); {
+                enterOuterAlt(_localctx, 3);
+                {
                 setState(79);
                 externalConstant();
-            }
+                }
                 break;
             case T__27:
                 _localctx = new ParenthesizedTermContext(_localctx);
-                enterOuterAlt(_localctx, 4); {
+                enterOuterAlt(_localctx, 4);
+                {
                 setState(80);
                 match(T__27);
                 setState(81);
                 expression(0);
                 setState(82);
                 match(T__28);
-            }
+                }
                 break;
             default:
                 throw new NoViableAltException(this);
             }
-        } catch (RecognitionException re) {
+        }
+        catch (RecognitionException re) {
             _localctx.exception = re;
             _errHandler.reportError(this, re);
             _errHandler.recover(this, re);
-        } finally {
+        }
+        finally {
             exitRule();
         }
         return _localctx;
@@ -860,135 +753,83 @@ public static class LiteralContext extends ParserRuleContext {
         public LiteralContext(ParserRuleContext parent, int invokingState) {
             super(parent, invokingState);
         }
-
-        @Override
-        public int getRuleIndex() {
-            return RULE_literal;
-        }
-
-        public LiteralContext() {
-        }
-
+        @Override public int getRuleIndex() { return RULE_literal; }
+     
+        public LiteralContext() { }
         public void copyFrom(LiteralContext ctx) {
             super.copyFrom(ctx);
         }
     }
-
     public static class TimeLiteralContext extends LiteralContext {
-        public TerminalNode TIME() {
-            return getToken(FHIRPathParser.TIME, 0);
-        }
-
-        public TimeLiteralContext(LiteralContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public TerminalNode TIME() { return getToken(FHIRPathParser.TIME, 0); }
+        public TimeLiteralContext(LiteralContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitTimeLiteral(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitTimeLiteral(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class NullLiteralContext extends LiteralContext {
-        public NullLiteralContext(LiteralContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public NullLiteralContext(LiteralContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitNullLiteral(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitNullLiteral(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class DateTimeLiteralContext extends LiteralContext {
-        public TerminalNode DATETIME() {
-            return getToken(FHIRPathParser.DATETIME, 0);
-        }
-
-        public DateTimeLiteralContext(LiteralContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public TerminalNode DATETIME() { return getToken(FHIRPathParser.DATETIME, 0); }
+        public DateTimeLiteralContext(LiteralContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitDateTimeLiteral(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitDateTimeLiteral(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class StringLiteralContext extends LiteralContext {
-        public TerminalNode STRING() {
-            return getToken(FHIRPathParser.STRING, 0);
-        }
-
-        public StringLiteralContext(LiteralContext ctx) {
-            copyFrom(ctx);
+        public TerminalNode STRING() { return getToken(FHIRPathParser.STRING, 0); }
+        public StringLiteralContext(LiteralContext ctx) { copyFrom(ctx); }
+        @Override
+        public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitStringLiteral(this);
+            else return visitor.visitChildren(this);
         }
-
+    }
+    public static class DateLiteralContext extends LiteralContext {
+        public TerminalNode DATE() { return getToken(FHIRPathParser.DATE, 0); }
+        public DateLiteralContext(LiteralContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitStringLiteral(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitDateLiteral(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class BooleanLiteralContext extends LiteralContext {
-        public BooleanLiteralContext(LiteralContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public BooleanLiteralContext(LiteralContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitBooleanLiteral(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitBooleanLiteral(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class NumberLiteralContext extends LiteralContext {
-        public TerminalNode NUMBER() {
-            return getToken(FHIRPathParser.NUMBER, 0);
-        }
-
-        public NumberLiteralContext(LiteralContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public TerminalNode NUMBER() { return getToken(FHIRPathParser.NUMBER, 0); }
+        public NumberLiteralContext(LiteralContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitNumberLiteral(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitNumberLiteral(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class QuantityLiteralContext extends LiteralContext {
         public QuantityContext quantity() {
-            return getRuleContext(QuantityContext.class, 0);
+            return getRuleContext(QuantityContext.class,0);
         }
-
-        public QuantityLiteralContext(LiteralContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public QuantityLiteralContext(LiteralContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitQuantityLiteral(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitQuantityLiteral(this);
+            else return visitor.visitChildren(this);
         }
     }
 
@@ -997,71 +838,91 @@ public final LiteralContext literal() throws RecognitionException {
         enterRule(_localctx, 4, RULE_literal);
         int _la;
         try {
-            setState(94);
+            setState(95);
             _errHandler.sync(this);
-            switch (getInterpreter().adaptivePredict(_input, 4, _ctx)) {
+            switch ( getInterpreter().adaptivePredict(_input,4,_ctx) ) {
             case 1:
                 _localctx = new NullLiteralContext(_localctx);
-                enterOuterAlt(_localctx, 1); {
+                enterOuterAlt(_localctx, 1);
+                {
                 setState(86);
                 match(T__29);
                 setState(87);
                 match(T__30);
-            }
+                }
                 break;
             case 2:
                 _localctx = new BooleanLiteralContext(_localctx);
-                enterOuterAlt(_localctx, 2); {
+                enterOuterAlt(_localctx, 2);
+                {
                 setState(88);
                 _la = _input.LA(1);
-                if (!(_la == T__31 || _la == T__32)) {
-                    _errHandler.recoverInline(this);
-                } else {
+                if ( !(_la==T__31 || _la==T__32) ) {
+                _errHandler.recoverInline(this);
+                }
+                else {
+                    if ( _input.LA(1)==Token.EOF ) matchedEOF = true;
+                    _errHandler.reportMatch(this);
                     consume();
                 }
-            }
+                }
                 break;
             case 3:
                 _localctx = new StringLiteralContext(_localctx);
-                enterOuterAlt(_localctx, 3); {
+                enterOuterAlt(_localctx, 3);
+                {
                 setState(89);
                 match(STRING);
-            }
+                }
                 break;
             case 4:
                 _localctx = new NumberLiteralContext(_localctx);
-                enterOuterAlt(_localctx, 4); {
+                enterOuterAlt(_localctx, 4);
+                {
                 setState(90);
                 match(NUMBER);
-            }
+                }
                 break;
             case 5:
-                _localctx = new DateTimeLiteralContext(_localctx);
-                enterOuterAlt(_localctx, 5); {
+                _localctx = new DateLiteralContext(_localctx);
+                enterOuterAlt(_localctx, 5);
+                {
                 setState(91);
-                match(DATETIME);
-            }
+                match(DATE);
+                }
                 break;
             case 6:
-                _localctx = new TimeLiteralContext(_localctx);
-                enterOuterAlt(_localctx, 6); {
+                _localctx = new DateTimeLiteralContext(_localctx);
+                enterOuterAlt(_localctx, 6);
+                {
                 setState(92);
-                match(TIME);
-            }
+                match(DATETIME);
+                }
                 break;
             case 7:
-                _localctx = new QuantityLiteralContext(_localctx);
-                enterOuterAlt(_localctx, 7); {
+                _localctx = new TimeLiteralContext(_localctx);
+                enterOuterAlt(_localctx, 7);
+                {
                 setState(93);
+                match(TIME);
+                }
+                break;
+            case 8:
+                _localctx = new QuantityLiteralContext(_localctx);
+                enterOuterAlt(_localctx, 8);
+                {
+                setState(94);
                 quantity();
-            }
+                }
                 break;
             }
-        } catch (RecognitionException re) {
+        }
+        catch (RecognitionException re) {
             _localctx.exception = re;
             _errHandler.reportError(this, re);
             _errHandler.recover(this, re);
-        } finally {
+        }
+        finally {
             exitRule();
         }
         return _localctx;
@@ -1069,24 +930,17 @@ public final LiteralContext literal() throws RecognitionException {
 
     public static class ExternalConstantContext extends ParserRuleContext {
         public IdentifierContext identifier() {
-            return getRuleContext(IdentifierContext.class, 0);
+            return getRuleContext(IdentifierContext.class,0);
         }
-
+        public TerminalNode STRING() { return getToken(FHIRPathParser.STRING, 0); }
         public ExternalConstantContext(ParserRuleContext parent, int invokingState) {
             super(parent, invokingState);
         }
-
-        @Override
-        public int getRuleIndex() {
-            return RULE_externalConstant;
-        }
-
+        @Override public int getRuleIndex() { return RULE_externalConstant; }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitExternalConstant(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitExternalConstant(this);
+            else return visitor.visitChildren(this);
         }
     }
 
@@ -1096,16 +950,39 @@ public final ExternalConstantContext externalConstant() throws RecognitionExcept
         try {
             enterOuterAlt(_localctx, 1);
             {
-                setState(96);
-                match(T__33);
-                setState(97);
+            setState(97);
+            match(T__33);
+            setState(100);
+            _errHandler.sync(this);
+            switch (_input.LA(1)) {
+            case T__10:
+            case T__11:
+            case T__21:
+            case T__22:
+            case IDENTIFIER:
+            case DELIMITEDIDENTIFIER:
+                {
+                setState(98);
                 identifier();
+                }
+                break;
+            case STRING:
+                {
+                setState(99);
+                match(STRING);
+                }
+                break;
+            default:
+                throw new NoViableAltException(this);
+            }
             }
-        } catch (RecognitionException re) {
+        }
+        catch (RecognitionException re) {
             _localctx.exception = re;
             _errHandler.reportError(this, re);
             _errHandler.recover(this, re);
-        } finally {
+        }
+        finally {
             exitRule();
         }
         return _localctx;
@@ -1115,95 +992,57 @@ public static class InvocationContext extends ParserRuleContext {
         public InvocationContext(ParserRuleContext parent, int invokingState) {
             super(parent, invokingState);
         }
-
-        @Override
-        public int getRuleIndex() {
-            return RULE_invocation;
-        }
-
-        public InvocationContext() {
-        }
-
+        @Override public int getRuleIndex() { return RULE_invocation; }
+     
+        public InvocationContext() { }
         public void copyFrom(InvocationContext ctx) {
             super.copyFrom(ctx);
         }
     }
-
     public static class TotalInvocationContext extends InvocationContext {
-        public TotalInvocationContext(InvocationContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public TotalInvocationContext(InvocationContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitTotalInvocation(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitTotalInvocation(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class ThisInvocationContext extends InvocationContext {
-        public ThisInvocationContext(InvocationContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public ThisInvocationContext(InvocationContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitThisInvocation(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitThisInvocation(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class IndexInvocationContext extends InvocationContext {
-        public IndexInvocationContext(InvocationContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public IndexInvocationContext(InvocationContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitIndexInvocation(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitIndexInvocation(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class FunctionInvocationContext extends InvocationContext {
         public FunctionContext function() {
-            return getRuleContext(FunctionContext.class, 0);
+            return getRuleContext(FunctionContext.class,0);
         }
-
-        public FunctionInvocationContext(InvocationContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public FunctionInvocationContext(InvocationContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitFunctionInvocation(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitFunctionInvocation(this);
+            else return visitor.visitChildren(this);
         }
     }
-
     public static class MemberInvocationContext extends InvocationContext {
         public IdentifierContext identifier() {
-            return getRuleContext(IdentifierContext.class, 0);
+            return getRuleContext(IdentifierContext.class,0);
         }
-
-        public MemberInvocationContext(InvocationContext ctx) {
-            copyFrom(ctx);
-        }
-
+        public MemberInvocationContext(InvocationContext ctx) { copyFrom(ctx); }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitMemberInvocation(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitMemberInvocation(this);
+            else return visitor.visitChildren(this);
         }
     }
 
@@ -1211,50 +1050,57 @@ public final InvocationContext invocation() throws RecognitionException {
         InvocationContext _localctx = new InvocationContext(_ctx, getState());
         enterRule(_localctx, 8, RULE_invocation);
         try {
-            setState(104);
+            setState(107);
             _errHandler.sync(this);
-            switch (getInterpreter().adaptivePredict(_input, 5, _ctx)) {
+            switch ( getInterpreter().adaptivePredict(_input,6,_ctx) ) {
             case 1:
                 _localctx = new MemberInvocationContext(_localctx);
-                enterOuterAlt(_localctx, 1); {
-                setState(99);
+                enterOuterAlt(_localctx, 1);
+                {
+                setState(102);
                 identifier();
-            }
+                }
                 break;
             case 2:
                 _localctx = new FunctionInvocationContext(_localctx);
-                enterOuterAlt(_localctx, 2); {
-                setState(100);
+                enterOuterAlt(_localctx, 2);
+                {
+                setState(103);
                 function();
-            }
+                }
                 break;
             case 3:
                 _localctx = new ThisInvocationContext(_localctx);
-                enterOuterAlt(_localctx, 3); {
-                setState(101);
+                enterOuterAlt(_localctx, 3);
+                {
+                setState(104);
                 match(T__34);
-            }
+                }
                 break;
             case 4:
                 _localctx = new IndexInvocationContext(_localctx);
-                enterOuterAlt(_localctx, 4); {
-                setState(102);
+                enterOuterAlt(_localctx, 4);
+                {
+                setState(105);
                 match(T__35);
-            }
+                }
                 break;
             case 5:
                 _localctx = new TotalInvocationContext(_localctx);
-                enterOuterAlt(_localctx, 5); {
-                setState(103);
+                enterOuterAlt(_localctx, 5);
+                {
+                setState(106);
                 match(T__36);
-            }
+                }
                 break;
             }
-        } catch (RecognitionException re) {
+        }
+        catch (RecognitionException re) {
             _localctx.exception = re;
             _errHandler.reportError(this, re);
             _errHandler.recover(this, re);
-        } finally {
+        }
+        finally {
             exitRule();
         }
         return _localctx;
@@ -1262,28 +1108,19 @@ public final InvocationContext invocation() throws RecognitionException {
 
     public static class FunctionContext extends ParserRuleContext {
         public IdentifierContext identifier() {
-            return getRuleContext(IdentifierContext.class, 0);
+            return getRuleContext(IdentifierContext.class,0);
         }
-
         public ParamListContext paramList() {
-            return getRuleContext(ParamListContext.class, 0);
+            return getRuleContext(ParamListContext.class,0);
         }
-
         public FunctionContext(ParserRuleContext parent, int invokingState) {
             super(parent, invokingState);
         }
-
-        @Override
-        public int getRuleIndex() {
-            return RULE_function;
-        }
-
+        @Override public int getRuleIndex() { return RULE_function; }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitFunction(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitFunction(this);
+            else return visitor.visitChildren(this);
         }
     }
 
@@ -1294,29 +1131,30 @@ public final FunctionContext function() throws RecognitionException {
         try {
             enterOuterAlt(_localctx, 1);
             {
-                setState(106);
-                identifier();
-                setState(107);
-                match(T__27);
-                setState(109);
-                _la = _input.LA(1);
-                if ((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__3) | (1L << T__4) | (1L << T__10) | (1L << T__11) | (1L << T__27) | (1L << T__29)
-                        | (1L << T__31) | (1L << T__32) | (1L << T__33) | (1L << T__34) | (1L << T__35) | (1L << T__36) | (1L << DATETIME) | (1L << TIME)
-                        | (1L << IDENTIFIER) | (1L << DELIMITEDIDENTIFIER) | (1L << STRING) | (1L << NUMBER))) != 0)) {
-                    {
-                        setState(108);
-                        paramList();
-                    }
+            setState(109);
+            identifier();
+            setState(110);
+            match(T__27);
+            setState(112);
+            _errHandler.sync(this);
+            _la = _input.LA(1);
+            if ((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__3) | (1L << T__4) | (1L << T__10) | (1L << T__11) | (1L << T__21) | (1L << T__22) | (1L << T__27) | (1L << T__29) | (1L << T__31) | (1L << T__32) | (1L << T__33) | (1L << T__34) | (1L << T__35) | (1L << T__36) | (1L << DATE) | (1L << DATETIME) | (1L << TIME) | (1L << IDENTIFIER) | (1L << DELIMITEDIDENTIFIER) | (1L << STRING) | (1L << NUMBER))) != 0)) {
+                {
+                setState(111);
+                paramList();
                 }
+            }
 
-                setState(111);
-                match(T__28);
+            setState(114);
+            match(T__28);
             }
-        } catch (RecognitionException re) {
+        }
+        catch (RecognitionException re) {
             _localctx.exception = re;
             _errHandler.reportError(this, re);
             _errHandler.recover(this, re);
-        } finally {
+        }
+        finally {
             exitRule();
         }
         return _localctx;
@@ -1326,26 +1164,17 @@ public static class ParamListContext extends ParserRuleContext {
         public List<ExpressionContext> expression() {
             return getRuleContexts(ExpressionContext.class);
         }
-
         public ExpressionContext expression(int i) {
-            return getRuleContext(ExpressionContext.class, i);
+            return getRuleContext(ExpressionContext.class,i);
         }
-
         public ParamListContext(ParserRuleContext parent, int invokingState) {
             super(parent, invokingState);
         }
-
-        @Override
-        public int getRuleIndex() {
-            return RULE_paramList;
-        }
-
+        @Override public int getRuleIndex() { return RULE_paramList; }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitParamList(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitParamList(this);
+            else return visitor.visitChildren(this);
         }
     }
 
@@ -1356,59 +1185,50 @@ public final ParamListContext paramList() throws RecognitionException {
         try {
             enterOuterAlt(_localctx, 1);
             {
-                setState(113);
-                expression(0);
+            setState(116);
+            expression(0);
+            setState(121);
+            _errHandler.sync(this);
+            _la = _input.LA(1);
+            while (_la==T__37) {
+                {
+                {
+                setState(117);
+                match(T__37);
                 setState(118);
+                expression(0);
+                }
+                }
+                setState(123);
                 _errHandler.sync(this);
                 _la = _input.LA(1);
-                while (_la == T__37) {
-                    {
-                        {
-                            setState(114);
-                            match(T__37);
-                            setState(115);
-                            expression(0);
-                        }
-                    }
-                    setState(120);
-                    _errHandler.sync(this);
-                    _la = _input.LA(1);
-                }
             }
-        } catch (RecognitionException re) {
+            }
+        }
+        catch (RecognitionException re) {
             _localctx.exception = re;
             _errHandler.reportError(this, re);
             _errHandler.recover(this, re);
-        } finally {
+        }
+        finally {
             exitRule();
         }
         return _localctx;
     }
 
     public static class QuantityContext extends ParserRuleContext {
-        public TerminalNode NUMBER() {
-            return getToken(FHIRPathParser.NUMBER, 0);
-        }
-
+        public TerminalNode NUMBER() { return getToken(FHIRPathParser.NUMBER, 0); }
         public UnitContext unit() {
-            return getRuleContext(UnitContext.class, 0);
+            return getRuleContext(UnitContext.class,0);
         }
-
         public QuantityContext(ParserRuleContext parent, int invokingState) {
             super(parent, invokingState);
         }
-
-        @Override
-        public int getRuleIndex() {
-            return RULE_quantity;
-        }
-
+        @Override public int getRuleIndex() { return RULE_quantity; }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitQuantity(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitQuantity(this);
+            else return visitor.visitChildren(this);
         }
     }
 
@@ -1418,23 +1238,26 @@ public final QuantityContext quantity() throws RecognitionException {
         try {
             enterOuterAlt(_localctx, 1);
             {
-                setState(121);
-                match(NUMBER);
-                setState(123);
-                _errHandler.sync(this);
-                switch (getInterpreter().adaptivePredict(_input, 8, _ctx)) {
-                case 1: {
-                    setState(122);
-                    unit();
-                }
-                    break;
+            setState(124);
+            match(NUMBER);
+            setState(126);
+            _errHandler.sync(this);
+            switch ( getInterpreter().adaptivePredict(_input,9,_ctx) ) {
+            case 1:
+                {
+                setState(125);
+                unit();
                 }
+                break;
             }
-        } catch (RecognitionException re) {
+            }
+        }
+        catch (RecognitionException re) {
             _localctx.exception = re;
             _errHandler.reportError(this, re);
             _errHandler.recover(this, re);
-        } finally {
+        }
+        finally {
             exitRule();
         }
         return _localctx;
@@ -1442,32 +1265,20 @@ public final QuantityContext quantity() throws RecognitionException {
 
     public static class UnitContext extends ParserRuleContext {
         public DateTimePrecisionContext dateTimePrecision() {
-            return getRuleContext(DateTimePrecisionContext.class, 0);
+            return getRuleContext(DateTimePrecisionContext.class,0);
         }
-
         public PluralDateTimePrecisionContext pluralDateTimePrecision() {
-            return getRuleContext(PluralDateTimePrecisionContext.class, 0);
-        }
-
-        public TerminalNode STRING() {
-            return getToken(FHIRPathParser.STRING, 0);
+            return getRuleContext(PluralDateTimePrecisionContext.class,0);
         }
-
+        public TerminalNode STRING() { return getToken(FHIRPathParser.STRING, 0); }
         public UnitContext(ParserRuleContext parent, int invokingState) {
             super(parent, invokingState);
         }
-
-        @Override
-        public int getRuleIndex() {
-            return RULE_unit;
-        }
-
+        @Override public int getRuleIndex() { return RULE_unit; }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitUnit(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitUnit(this);
+            else return visitor.visitChildren(this);
         }
     }
 
@@ -1475,7 +1286,8 @@ public final UnitContext unit() throws RecognitionException {
         UnitContext _localctx = new UnitContext(_ctx, getState());
         enterRule(_localctx, 16, RULE_unit);
         try {
-            setState(128);
+            setState(131);
+            _errHandler.sync(this);
             switch (_input.LA(1)) {
             case T__38:
             case T__39:
@@ -1485,10 +1297,11 @@ public final UnitContext unit() throws RecognitionException {
             case T__43:
             case T__44:
             case T__45:
-                enterOuterAlt(_localctx, 1); {
-                setState(125);
+                enterOuterAlt(_localctx, 1);
+                {
+                setState(128);
                 dateTimePrecision();
-            }
+                }
                 break;
             case T__46:
             case T__47:
@@ -1498,25 +1311,29 @@ public final UnitContext unit() throws RecognitionException {
             case T__51:
             case T__52:
             case T__53:
-                enterOuterAlt(_localctx, 2); {
-                setState(126);
+                enterOuterAlt(_localctx, 2);
+                {
+                setState(129);
                 pluralDateTimePrecision();
-            }
+                }
                 break;
             case STRING:
-                enterOuterAlt(_localctx, 3); {
-                setState(127);
+                enterOuterAlt(_localctx, 3);
+                {
+                setState(130);
                 match(STRING);
-            }
+                }
                 break;
             default:
                 throw new NoViableAltException(this);
             }
-        } catch (RecognitionException re) {
+        }
+        catch (RecognitionException re) {
             _localctx.exception = re;
             _errHandler.reportError(this, re);
             _errHandler.recover(this, re);
-        } finally {
+        }
+        finally {
             exitRule();
         }
         return _localctx;
@@ -1526,18 +1343,11 @@ public static class DateTimePrecisionContext extends ParserRuleContext {
         public DateTimePrecisionContext(ParserRuleContext parent, int invokingState) {
             super(parent, invokingState);
         }
-
-        @Override
-        public int getRuleIndex() {
-            return RULE_dateTimePrecision;
-        }
-
+        @Override public int getRuleIndex() { return RULE_dateTimePrecision; }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitDateTimePrecision(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitDateTimePrecision(this);
+            else return visitor.visitChildren(this);
         }
     }
 
@@ -1548,20 +1358,24 @@ public final DateTimePrecisionContext dateTimePrecision() throws RecognitionExce
         try {
             enterOuterAlt(_localctx, 1);
             {
-                setState(130);
-                _la = _input.LA(1);
-                if (!((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__38) | (1L << T__39) | (1L << T__40) | (1L << T__41) | (1L << T__42) | (1L << T__43)
-                        | (1L << T__44) | (1L << T__45))) != 0))) {
-                    _errHandler.recoverInline(this);
-                } else {
-                    consume();
-                }
+            setState(133);
+            _la = _input.LA(1);
+            if ( !((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__38) | (1L << T__39) | (1L << T__40) | (1L << T__41) | (1L << T__42) | (1L << T__43) | (1L << T__44) | (1L << T__45))) != 0)) ) {
+            _errHandler.recoverInline(this);
+            }
+            else {
+                if ( _input.LA(1)==Token.EOF ) matchedEOF = true;
+                _errHandler.reportMatch(this);
+                consume();
             }
-        } catch (RecognitionException re) {
+            }
+        }
+        catch (RecognitionException re) {
             _localctx.exception = re;
             _errHandler.reportError(this, re);
             _errHandler.recover(this, re);
-        } finally {
+        }
+        finally {
             exitRule();
         }
         return _localctx;
@@ -1571,18 +1385,11 @@ public static class PluralDateTimePrecisionContext extends ParserRuleContext {
         public PluralDateTimePrecisionContext(ParserRuleContext parent, int invokingState) {
             super(parent, invokingState);
         }
-
-        @Override
-        public int getRuleIndex() {
-            return RULE_pluralDateTimePrecision;
-        }
-
+        @Override public int getRuleIndex() { return RULE_pluralDateTimePrecision; }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitPluralDateTimePrecision(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitPluralDateTimePrecision(this);
+            else return visitor.visitChildren(this);
         }
     }
 
@@ -1593,20 +1400,24 @@ public final PluralDateTimePrecisionContext pluralDateTimePrecision() throws Rec
         try {
             enterOuterAlt(_localctx, 1);
             {
-                setState(132);
-                _la = _input.LA(1);
-                if (!((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__46) | (1L << T__47) | (1L << T__48) | (1L << T__49) | (1L << T__50) | (1L << T__51)
-                        | (1L << T__52) | (1L << T__53))) != 0))) {
-                    _errHandler.recoverInline(this);
-                } else {
-                    consume();
-                }
+            setState(135);
+            _la = _input.LA(1);
+            if ( !((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__46) | (1L << T__47) | (1L << T__48) | (1L << T__49) | (1L << T__50) | (1L << T__51) | (1L << T__52) | (1L << T__53))) != 0)) ) {
+            _errHandler.recoverInline(this);
+            }
+            else {
+                if ( _input.LA(1)==Token.EOF ) matchedEOF = true;
+                _errHandler.reportMatch(this);
+                consume();
             }
-        } catch (RecognitionException re) {
+            }
+        }
+        catch (RecognitionException re) {
             _localctx.exception = re;
             _errHandler.reportError(this, re);
             _errHandler.recover(this, re);
-        } finally {
+        }
+        finally {
             exitRule();
         }
         return _localctx;
@@ -1614,24 +1425,16 @@ public final PluralDateTimePrecisionContext pluralDateTimePrecision() throws Rec
 
     public static class TypeSpecifierContext extends ParserRuleContext {
         public QualifiedIdentifierContext qualifiedIdentifier() {
-            return getRuleContext(QualifiedIdentifierContext.class, 0);
+            return getRuleContext(QualifiedIdentifierContext.class,0);
         }
-
         public TypeSpecifierContext(ParserRuleContext parent, int invokingState) {
             super(parent, invokingState);
         }
-
-        @Override
-        public int getRuleIndex() {
-            return RULE_typeSpecifier;
-        }
-
+        @Override public int getRuleIndex() { return RULE_typeSpecifier; }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitTypeSpecifier(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitTypeSpecifier(this);
+            else return visitor.visitChildren(this);
         }
     }
 
@@ -1641,14 +1444,16 @@ public final TypeSpecifierContext typeSpecifier() throws RecognitionException {
         try {
             enterOuterAlt(_localctx, 1);
             {
-                setState(134);
-                qualifiedIdentifier();
+            setState(137);
+            qualifiedIdentifier();
             }
-        } catch (RecognitionException re) {
+        }
+        catch (RecognitionException re) {
             _localctx.exception = re;
             _errHandler.reportError(this, re);
             _errHandler.recover(this, re);
-        } finally {
+        }
+        finally {
             exitRule();
         }
         return _localctx;
@@ -1658,26 +1463,17 @@ public static class QualifiedIdentifierContext extends ParserRuleContext {
         public List<IdentifierContext> identifier() {
             return getRuleContexts(IdentifierContext.class);
         }
-
         public IdentifierContext identifier(int i) {
-            return getRuleContext(IdentifierContext.class, i);
+            return getRuleContext(IdentifierContext.class,i);
         }
-
         public QualifiedIdentifierContext(ParserRuleContext parent, int invokingState) {
             super(parent, invokingState);
         }
-
-        @Override
-        public int getRuleIndex() {
-            return RULE_qualifiedIdentifier;
-        }
-
+        @Override public int getRuleIndex() { return RULE_qualifiedIdentifier; }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitQualifiedIdentifier(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitQualifiedIdentifier(this);
+            else return visitor.visitChildren(this);
         }
     }
 
@@ -1688,61 +1484,50 @@ public final QualifiedIdentifierContext qualifiedIdentifier() throws Recognition
             int _alt;
             enterOuterAlt(_localctx, 1);
             {
-                setState(136);
-                identifier();
-                setState(141);
-                _errHandler.sync(this);
-                _alt = getInterpreter().adaptivePredict(_input, 10, _ctx);
-                while (_alt != 2 && _alt != org.antlr.v4.runtime.atn.ATN.INVALID_ALT_NUMBER) {
-                    if (_alt == 1) {
-                        {
-                            {
-                                setState(137);
-                                match(T__0);
-                                setState(138);
-                                identifier();
-                            }
-                        }
+            setState(139);
+            identifier();
+            setState(144);
+            _errHandler.sync(this);
+            _alt = getInterpreter().adaptivePredict(_input,11,_ctx);
+            while ( _alt!=2 && _alt!=org.antlr.v4.runtime.atn.ATN.INVALID_ALT_NUMBER ) {
+                if ( _alt==1 ) {
+                    {
+                    {
+                    setState(140);
+                    match(T__0);
+                    setState(141);
+                    identifier();
                     }
-                    setState(143);
-                    _errHandler.sync(this);
-                    _alt = getInterpreter().adaptivePredict(_input, 10, _ctx);
+                    } 
                 }
+                setState(146);
+                _errHandler.sync(this);
+                _alt = getInterpreter().adaptivePredict(_input,11,_ctx);
             }
-        } catch (RecognitionException re) {
+            }
+        }
+        catch (RecognitionException re) {
             _localctx.exception = re;
             _errHandler.reportError(this, re);
             _errHandler.recover(this, re);
-        } finally {
+        }
+        finally {
             exitRule();
         }
         return _localctx;
     }
 
     public static class IdentifierContext extends ParserRuleContext {
-        public TerminalNode IDENTIFIER() {
-            return getToken(FHIRPathParser.IDENTIFIER, 0);
-        }
-
-        public TerminalNode DELIMITEDIDENTIFIER() {
-            return getToken(FHIRPathParser.DELIMITEDIDENTIFIER, 0);
-        }
-
+        public TerminalNode IDENTIFIER() { return getToken(FHIRPathParser.IDENTIFIER, 0); }
+        public TerminalNode DELIMITEDIDENTIFIER() { return getToken(FHIRPathParser.DELIMITEDIDENTIFIER, 0); }
         public IdentifierContext(ParserRuleContext parent, int invokingState) {
             super(parent, invokingState);
         }
-
-        @Override
-        public int getRuleIndex() {
-            return RULE_identifier;
-        }
-
+        @Override public int getRuleIndex() { return RULE_identifier; }
         @Override
         public <T> T accept(ParseTreeVisitor<? extends T> visitor) {
-            if (visitor instanceof FHIRPathVisitor)
-                return ((FHIRPathVisitor<? extends T>) visitor).visitIdentifier(this);
-            else
-                return visitor.visitChildren(this);
+            if ( visitor instanceof FHIRPathVisitor ) return ((FHIRPathVisitor<? extends T>)visitor).visitIdentifier(this);
+            else return visitor.visitChildren(this);
         }
     }
 
@@ -1753,19 +1538,24 @@ public final IdentifierContext identifier() throws RecognitionException {
         try {
             enterOuterAlt(_localctx, 1);
             {
-                setState(144);
-                _la = _input.LA(1);
-                if (!((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__10) | (1L << T__11) | (1L << IDENTIFIER) | (1L << DELIMITEDIDENTIFIER))) != 0))) {
-                    _errHandler.recoverInline(this);
-                } else {
-                    consume();
-                }
+            setState(147);
+            _la = _input.LA(1);
+            if ( !((((_la) & ~0x3f) == 0 && ((1L << _la) & ((1L << T__10) | (1L << T__11) | (1L << T__21) | (1L << T__22) | (1L << IDENTIFIER) | (1L << DELIMITEDIDENTIFIER))) != 0)) ) {
+            _errHandler.recoverInline(this);
+            }
+            else {
+                if ( _input.LA(1)==Token.EOF ) matchedEOF = true;
+                _errHandler.reportMatch(this);
+                consume();
+            }
             }
-        } catch (RecognitionException re) {
+        }
+        catch (RecognitionException re) {
             _localctx.exception = re;
             _errHandler.reportError(this, re);
             _errHandler.recover(this, re);
-        } finally {
+        }
+        finally {
             exitRule();
         }
         return _localctx;
@@ -1774,11 +1564,10 @@ public final IdentifierContext identifier() throws RecognitionException {
     public boolean sempred(RuleContext _localctx, int ruleIndex, int predIndex) {
         switch (ruleIndex) {
         case 0:
-            return expression_sempred((ExpressionContext) _localctx, predIndex);
+            return expression_sempred((ExpressionContext)_localctx, predIndex);
         }
         return true;
     }
-
     private boolean expression_sempred(ExpressionContext _localctx, int predIndex) {
         switch (predIndex) {
         case 0:
@@ -1809,37 +1598,57 @@ private boolean expression_sempred(ExpressionContext _localctx, int predIndex) {
         return true;
     }
 
-    public static final String _serializedATN = "\3\u0430\ud6d1\u8206\uad2d\u4417\uaef1\u8d80\uaadd\3A\u0095\4\2\t\2\4"
-            + "\3\t\3\4\4\t\4\4\5\t\5\4\6\t\6\4\7\t\7\4\b\t\b\4\t\t\t\4\n\t\n\4\13\t" + "\13\4\f\t\f\4\r\t\r\4\16\t\16\4\17\t\17\3\2\3\2\3\2\3\2\5\2#\n\2\3\2\3"
-            + "\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2"
-            + "\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3" + "\2\3\2\7\2K\n\2\f\2\16\2N\13\2\3\3\3\3\3\3\3\3\3\3\3\3\3\3\5\3W\n\3\3"
-            + "\4\3\4\3\4\3\4\3\4\3\4\3\4\3\4\5\4a\n\4\3\5\3\5\3\5\3\6\3\6\3\6\3\6\3" + "\6\5\6k\n\6\3\7\3\7\3\7\5\7p\n\7\3\7\3\7\3\b\3\b\3\b\7\bw\n\b\f\b\16\b"
-            + "z\13\b\3\t\3\t\5\t~\n\t\3\n\3\n\3\n\5\n\u0083\n\n\3\13\3\13\3\f\3\f\3" + "\r\3\r\3\16\3\16\3\16\7\16\u008e\n\16\f\16\16\16\u0091\13\16\3\17\3\17"
-            + "\3\17\2\3\2\20\2\4\6\b\n\f\16\20\22\24\26\30\32\34\2\16\3\2\6\7\3\2\b" + "\13\4\2\6\7\f\f\3\2\20\23\3\2\24\27\3\2\30\31\3\2\33\34\3\2\r\16\3\2\""
-            + "#\3\2)\60\3\2\618\4\2\r\16;<\u00a6\2\"\3\2\2\2\4V\3\2\2\2\6`\3\2\2\2\b"
-            + "b\3\2\2\2\nj\3\2\2\2\fl\3\2\2\2\16s\3\2\2\2\20{\3\2\2\2\22\u0082\3\2\2"
-            + "\2\24\u0084\3\2\2\2\26\u0086\3\2\2\2\30\u0088\3\2\2\2\32\u008a\3\2\2\2"
-            + "\34\u0092\3\2\2\2\36\37\b\2\1\2\37#\5\4\3\2 !\t\2\2\2!#\5\2\2\r\"\36\3" + "\2\2\2\" \3\2\2\2#L\3\2\2\2$%\f\f\2\2%&\t\3\2\2&K\5\2\2\r\'(\f\13\2\2"
-            + "()\t\4\2\2)K\5\2\2\f*+\f\t\2\2+,\7\17\2\2,K\5\2\2\n-.\f\b\2\2./\t\5\2" + "\2/K\5\2\2\t\60\61\f\7\2\2\61\62\t\6\2\2\62K\5\2\2\b\63\64\f\6\2\2\64"
-            + "\65\t\7\2\2\65K\5\2\2\7\66\67\f\5\2\2\678\7\32\2\28K\5\2\2\69:\f\4\2\2"
-            + ":;\t\b\2\2;K\5\2\2\5<=\f\3\2\2=>\7\35\2\2>K\5\2\2\4?@\f\17\2\2@A\7\3\2" + "\2AK\5\n\6\2BC\f\16\2\2CD\7\4\2\2DE\5\2\2\2EF\7\5\2\2FK\3\2\2\2GH\f\n"
-            + "\2\2HI\t\t\2\2IK\5\30\r\2J$\3\2\2\2J\'\3\2\2\2J*\3\2\2\2J-\3\2\2\2J\60"
-            + "\3\2\2\2J\63\3\2\2\2J\66\3\2\2\2J9\3\2\2\2J<\3\2\2\2J?\3\2\2\2JB\3\2\2" + "\2JG\3\2\2\2KN\3\2\2\2LJ\3\2\2\2LM\3\2\2\2M\3\3\2\2\2NL\3\2\2\2OW\5\n"
-            + "\6\2PW\5\6\4\2QW\5\b\5\2RS\7\36\2\2ST\5\2\2\2TU\7\37\2\2UW\3\2\2\2VO\3" + "\2\2\2VP\3\2\2\2VQ\3\2\2\2VR\3\2\2\2W\5\3\2\2\2XY\7 \2\2Ya\7!\2\2Za\t"
-            + "\n\2\2[a\7=\2\2\\a\7>\2\2]a\79\2\2^a\7:\2\2_a\5\20\t\2`X\3\2\2\2`Z\3\2"
-            + "\2\2`[\3\2\2\2`\\\3\2\2\2`]\3\2\2\2`^\3\2\2\2`_\3\2\2\2a\7\3\2\2\2bc\7" + "$\2\2cd\5\34\17\2d\t\3\2\2\2ek\5\34\17\2fk\5\f\7\2gk\7%\2\2hk\7&\2\2i"
-            + "k\7\'\2\2je\3\2\2\2jf\3\2\2\2jg\3\2\2\2jh\3\2\2\2ji\3\2\2\2k\13\3\2\2" + "\2lm\5\34\17\2mo\7\36\2\2np\5\16\b\2on\3\2\2\2op\3\2\2\2pq\3\2\2\2qr\7"
-            + "\37\2\2r\r\3\2\2\2sx\5\2\2\2tu\7(\2\2uw\5\2\2\2vt\3\2\2\2wz\3\2\2\2xv" + "\3\2\2\2xy\3\2\2\2y\17\3\2\2\2zx\3\2\2\2{}\7>\2\2|~\5\22\n\2}|\3\2\2\2"
-            + "}~\3\2\2\2~\21\3\2\2\2\177\u0083\5\24\13\2\u0080\u0083\5\26\f\2\u0081" + "\u0083\7=\2\2\u0082\177\3\2\2\2\u0082\u0080\3\2\2\2\u0082\u0081\3\2\2"
-            + "\2\u0083\23\3\2\2\2\u0084\u0085\t\13\2\2\u0085\25\3\2\2\2\u0086\u0087" + "\t\f\2\2\u0087\27\3\2\2\2\u0088\u0089\5\32\16\2\u0089\31\3\2\2\2\u008a"
-            + "\u008f\5\34\17\2\u008b\u008c\7\3\2\2\u008c\u008e\5\34\17\2\u008d\u008b"
-            + "\3\2\2\2\u008e\u0091\3\2\2\2\u008f\u008d\3\2\2\2\u008f\u0090\3\2\2\2\u0090"
-            + "\33\3\2\2\2\u0091\u008f\3\2\2\2\u0092\u0093\t\r\2\2\u0093\35\3\2\2\2\r" + "\"JLV`jox}\u0082\u008f";
-    public static final ATN _ATN = new ATNDeserializer().deserialize(_serializedATN.toCharArray());
+    public static final String _serializedATN =
+        "\3\u608b\ua72a\u8133\ub9ed\u417c\u3be7\u7786\u5964\3B\u0098\4\2\t\2\4"+
+        "\3\t\3\4\4\t\4\4\5\t\5\4\6\t\6\4\7\t\7\4\b\t\b\4\t\t\t\4\n\t\n\4\13\t"+
+        "\13\4\f\t\f\4\r\t\r\4\16\t\16\4\17\t\17\3\2\3\2\3\2\3\2\5\2#\n\2\3\2\3"+
+        "\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2"+
+        "\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3\2\3"+
+        "\2\3\2\7\2K\n\2\f\2\16\2N\13\2\3\3\3\3\3\3\3\3\3\3\3\3\3\3\5\3W\n\3\3"+
+        "\4\3\4\3\4\3\4\3\4\3\4\3\4\3\4\3\4\5\4b\n\4\3\5\3\5\3\5\5\5g\n\5\3\6\3"+
+        "\6\3\6\3\6\3\6\5\6n\n\6\3\7\3\7\3\7\5\7s\n\7\3\7\3\7\3\b\3\b\3\b\7\bz"+
+        "\n\b\f\b\16\b}\13\b\3\t\3\t\5\t\u0081\n\t\3\n\3\n\3\n\5\n\u0086\n\n\3"+
+        "\13\3\13\3\f\3\f\3\r\3\r\3\16\3\16\3\16\7\16\u0091\n\16\f\16\16\16\u0094"+
+        "\13\16\3\17\3\17\3\17\2\3\2\20\2\4\6\b\n\f\16\20\22\24\26\30\32\34\2\16"+
+        "\3\2\6\7\3\2\b\13\4\2\6\7\f\f\3\2\20\23\3\2\24\27\3\2\30\31\3\2\33\34"+
+        "\3\2\r\16\3\2\"#\3\2)\60\3\2\618\5\2\r\16\30\31<=\2\u00ab\2\"\3\2\2\2"+
+        "\4V\3\2\2\2\6a\3\2\2\2\bc\3\2\2\2\nm\3\2\2\2\fo\3\2\2\2\16v\3\2\2\2\20"+
+        "~\3\2\2\2\22\u0085\3\2\2\2\24\u0087\3\2\2\2\26\u0089\3\2\2\2\30\u008b"+
+        "\3\2\2\2\32\u008d\3\2\2\2\34\u0095\3\2\2\2\36\37\b\2\1\2\37#\5\4\3\2 "+
+        "!\t\2\2\2!#\5\2\2\r\"\36\3\2\2\2\" \3\2\2\2#L\3\2\2\2$%\f\f\2\2%&\t\3"+
+        "\2\2&K\5\2\2\r\'(\f\13\2\2()\t\4\2\2)K\5\2\2\f*+\f\t\2\2+,\7\17\2\2,K"+
+        "\5\2\2\n-.\f\b\2\2./\t\5\2\2/K\5\2\2\t\60\61\f\7\2\2\61\62\t\6\2\2\62"+
+        "K\5\2\2\b\63\64\f\6\2\2\64\65\t\7\2\2\65K\5\2\2\7\66\67\f\5\2\2\678\7"+
+        "\32\2\28K\5\2\2\69:\f\4\2\2:;\t\b\2\2;K\5\2\2\5<=\f\3\2\2=>\7\35\2\2>"+
+        "K\5\2\2\4?@\f\17\2\2@A\7\3\2\2AK\5\n\6\2BC\f\16\2\2CD\7\4\2\2DE\5\2\2"+
+        "\2EF\7\5\2\2FK\3\2\2\2GH\f\n\2\2HI\t\t\2\2IK\5\30\r\2J$\3\2\2\2J\'\3\2"+
+        "\2\2J*\3\2\2\2J-\3\2\2\2J\60\3\2\2\2J\63\3\2\2\2J\66\3\2\2\2J9\3\2\2\2"+
+        "J<\3\2\2\2J?\3\2\2\2JB\3\2\2\2JG\3\2\2\2KN\3\2\2\2LJ\3\2\2\2LM\3\2\2\2"+
+        "M\3\3\2\2\2NL\3\2\2\2OW\5\n\6\2PW\5\6\4\2QW\5\b\5\2RS\7\36\2\2ST\5\2\2"+
+        "\2TU\7\37\2\2UW\3\2\2\2VO\3\2\2\2VP\3\2\2\2VQ\3\2\2\2VR\3\2\2\2W\5\3\2"+
+        "\2\2XY\7 \2\2Yb\7!\2\2Zb\t\n\2\2[b\7>\2\2\\b\7?\2\2]b\79\2\2^b\7:\2\2"+
+        "_b\7;\2\2`b\5\20\t\2aX\3\2\2\2aZ\3\2\2\2a[\3\2\2\2a\\\3\2\2\2a]\3\2\2"+
+        "\2a^\3\2\2\2a_\3\2\2\2a`\3\2\2\2b\7\3\2\2\2cf\7$\2\2dg\5\34\17\2eg\7>"+
+        "\2\2fd\3\2\2\2fe\3\2\2\2g\t\3\2\2\2hn\5\34\17\2in\5\f\7\2jn\7%\2\2kn\7"+
+        "&\2\2ln\7\'\2\2mh\3\2\2\2mi\3\2\2\2mj\3\2\2\2mk\3\2\2\2ml\3\2\2\2n\13"+
+        "\3\2\2\2op\5\34\17\2pr\7\36\2\2qs\5\16\b\2rq\3\2\2\2rs\3\2\2\2st\3\2\2"+
+        "\2tu\7\37\2\2u\r\3\2\2\2v{\5\2\2\2wx\7(\2\2xz\5\2\2\2yw\3\2\2\2z}\3\2"+
+        "\2\2{y\3\2\2\2{|\3\2\2\2|\17\3\2\2\2}{\3\2\2\2~\u0080\7?\2\2\177\u0081"+
+        "\5\22\n\2\u0080\177\3\2\2\2\u0080\u0081\3\2\2\2\u0081\21\3\2\2\2\u0082"+
+        "\u0086\5\24\13\2\u0083\u0086\5\26\f\2\u0084\u0086\7>\2\2\u0085\u0082\3"+
+        "\2\2\2\u0085\u0083\3\2\2\2\u0085\u0084\3\2\2\2\u0086\23\3\2\2\2\u0087"+
+        "\u0088\t\13\2\2\u0088\25\3\2\2\2\u0089\u008a\t\f\2\2\u008a\27\3\2\2\2"+
+        "\u008b\u008c\5\32\16\2\u008c\31\3\2\2\2\u008d\u0092\5\34\17\2\u008e\u008f"+
+        "\7\3\2\2\u008f\u0091\5\34\17\2\u0090\u008e\3\2\2\2\u0091\u0094\3\2\2\2"+
+        "\u0092\u0090\3\2\2\2\u0092\u0093\3\2\2\2\u0093\33\3\2\2\2\u0094\u0092"+
+        "\3\2\2\2\u0095\u0096\t\r\2\2\u0096\35\3\2\2\2\16\"JLVafmr{\u0080\u0085"+
+        "\u0092";
+    public static final ATN _ATN =
+        new ATNDeserializer().deserialize(_serializedATN.toCharArray());
     static {
         _decisionToDFA = new DFA[_ATN.getNumberOfDecisions()];
         for (int i = 0; i < _ATN.getNumberOfDecisions(); i++) {
             _decisionToDFA[i] = new DFA(_ATN.getDecisionState(i), i);
         }
     }
-}
+}
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathQuantityNode.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathQuantityNode.java
index 869f38e3c02..57481880b77 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathQuantityNode.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathQuantityNode.java
@@ -6,7 +6,6 @@
 
 package com.ibm.fhir.model.path;
 
-import static com.ibm.fhir.model.path.util.FHIRPathUtil.hasValueAndUnit;
 import static com.ibm.fhir.model.type.String.string;
 
 import java.math.BigDecimal;
@@ -17,34 +16,68 @@
 
 public class FHIRPathQuantityNode extends FHIRPathElementNode {    
     private final Quantity quantity;
+    private final String quantitySystem;
+    private final String quantityCode;
+    private final String quantityUnit;
+    private final BigDecimal quantityValue;
     
     protected FHIRPathQuantityNode(Builder builder) {
         super(builder);
         quantity = builder.quantity;
+        quantitySystem = getQuantitySystem(quantity);
+        quantityCode = getQuantityCode(quantity);
+        quantityUnit = getQuantityUnit(quantity);
+        quantityValue = getQuantityValue(quantity);
     }
     
     public Quantity quantity() {
         return quantity;
     }
     
+    public String getQuantitySystem() {
+        return quantitySystem;
+    }
+    
+    public String getQuantityCode() {
+        return quantityCode;
+    }
+    
+    public String getQuantityUnit() {
+        return quantityUnit;
+    }
+    
     public BigDecimal getQuantityValue() {
-        if (quantity.getValue() != null && quantity.getValue().getValue() != null) {
-            return quantity.getValue().getValue();
+        return quantityValue;
+    }
+
+    private String getQuantitySystem(Quantity quantity) {
+        if (quantity.getSystem() != null) {
+            return quantity.getSystem().getValue();
         }
         return null;
     }
     
-    public String getQuantityUnit() {
-        // prefer code over unit
-        if (quantity.getCode() != null && quantity.getCode().getValue() != null) {
+    private String getQuantityCode(Quantity quantity) {
+        if (quantity.getCode() != null) {
             return quantity.getCode().getValue();
         }
-        if (quantity.getUnit() != null && quantity.getUnit().getValue() != null) {
+        return null;
+    }
+
+    private String getQuantityUnit(Quantity quantity) {
+        if (quantity.getUnit() != null) {
             return quantity.getUnit().getValue();
         }
         return null;
     }
     
+    private BigDecimal getQuantityValue(Quantity quantity) {
+        if (quantity.getValue() != null) {
+            return quantity.getValue().getValue();
+        }
+        return null;
+    }
+    
     @Override
     public boolean isQuantityNode() {
         return true;
@@ -71,7 +104,7 @@ public Builder path(String path) {
             return (Builder) super.path(path);
         }
         
-        public Builder value(FHIRPathPrimitiveValue value) {
+        public Builder value(FHIRPathSystemValue value) {
             return (Builder) super.value(value);
         }
         
@@ -107,32 +140,48 @@ public FHIRPathQuantityNode subtract(FHIRPathQuantityNode node) {
     
     @Override
     public boolean isComparableTo(FHIRPathNode other) {
-        BigDecimal value = getQuantityValue();
-        if (other instanceof FHIRPathQuantityNode) {
-            return hasValueAndUnit(this) && 
-                    hasValueAndUnit((FHIRPathQuantityNode) other) && 
-                    // units must be equal
-                    getQuantityUnit().equals(((FHIRPathQuantityNode) other).getQuantityUnit());
-        }
-        if (other instanceof FHIRPathNumberValue || other.getValue() instanceof FHIRPathNumberValue) {
-            return value != null;
+        if (hasValue()) {
+            if (other instanceof FHIRPathQuantityValue) {
+                return getValue().isComparableTo(other);
+            }
+            if (other.getValue() instanceof FHIRPathQuantityValue) {
+                return getValue().isComparableTo(other.getValue());
+            }
+        } else if (other instanceof FHIRPathQuantityNode) {
+            return isComparableTo((FHIRPathQuantityNode) other);
+        } else if (other instanceof FHIRPathNumberValue || other.getValue() instanceof FHIRPathNumberValue) {
+            return getQuantityValue() != null;
         }
         return false;
     }
+    
+    private boolean isComparableTo(FHIRPathQuantityNode other) {
+        return getQuantityValue() != null && other.getQuantityValue() != null && 
+                ((getQuantitySystem() !=null && other.getQuantitySystem() != null && getQuantitySystem().equals(other.getQuantitySystem()) && 
+                        getQuantityCode() != null && other.getQuantityCode() != null && getQuantityCode().equals(other.getQuantityCode())) || 
+                        (getQuantityUnit() != null && other.getQuantityUnit() != null && getQuantityUnit().equals(other.getQuantityUnit())));
+    }
 
     @Override
     public int compareTo(FHIRPathNode other) {
         if (!isComparableTo(other)) {
             throw new IllegalArgumentException();
         }
-        BigDecimal value = getQuantityValue();
-        if (other instanceof FHIRPathNumberValue) {
-            return value.compareTo(((FHIRPathNumberValue) other).decimal());
-        }
-        if (other.getValue() instanceof FHIRPathNumberValue) {
-            return value.compareTo(((FHIRPathNumberValue) other.getValue()).decimal());
+        if (hasValue()) {
+            if (other instanceof FHIRPathQuantityValue) {
+                return getValue().compareTo(other);
+            }
+            if (other.getValue() instanceof FHIRPathQuantityValue) {
+                return getValue().compareTo(other.getValue());
+            }
+        } else if (other instanceof FHIRPathQuantityNode) {
+            return getQuantityValue().compareTo(((FHIRPathQuantityNode) other).getQuantityValue());
+        } else if (other instanceof FHIRPathNumberValue) {
+            return getQuantityValue().compareTo(((FHIRPathNumberValue) other).decimal());
+        } else if (other.getValue() instanceof FHIRPathNumberValue) {
+            return getQuantityValue().compareTo(((FHIRPathNumberValue) other.getValue()).decimal());
         }
-        return value.compareTo(((FHIRPathQuantityNode) other).getQuantityValue());
+        throw new IllegalStateException();
     }
 
     @Override
@@ -147,4 +196,4 @@ public String toString() {
         sb.append("'");
         return sb.toString();
     }
-}
+}
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathQuantityValue.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathQuantityValue.java
new file mode 100644
index 00000000000..4b9202c5a4d
--- /dev/null
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathQuantityValue.java
@@ -0,0 +1,192 @@
+/*
+ * (C) Copyright IBM Corp. 2019
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.ibm.fhir.model.path;
+
+import java.math.BigDecimal;
+import java.util.Collection;
+import java.util.Objects;
+
+import com.ibm.fhir.model.path.visitor.FHIRPathNodeVisitor;
+import com.ibm.fhir.model.type.Quantity;
+
+public class FHIRPathQuantityValue extends FHIRPathAbstractNode implements FHIRPathSystemValue {
+    private final BigDecimal value;
+    private final String unit;
+
+    protected FHIRPathQuantityValue(Builder builder) {
+        super(builder);
+        this.value = builder.value;
+        this.unit = builder.unit;
+    }
+    
+    @Override
+    public boolean isQuantityValue() {
+        return true;
+    }
+    
+    public BigDecimal value() {
+        return value;
+    }
+    
+    public String unit() {
+        return unit;
+    }
+    
+    public static FHIRPathQuantityValue quantityValue(Quantity quantity) {
+        if (quantity.getValue() != null && 
+            quantity.getValue().getValue() != null && 
+            quantity.getSystem() != null && 
+            "http://unitsofmeasure.org".equals(quantity.getSystem().getValue()) && 
+            quantity.getCode() != null && 
+            quantity.getCode().getValue() != null) {
+            BigDecimal value = quantity.getValue().getValue();
+            String unit = getUnit(quantity.getCode().getValue());
+            return quantityValue(value, unit);
+        }
+        return null;
+    }
+
+    private static String getUnit(String code) {
+        switch (code) {
+        case "a":
+            return "year";
+        case "mo":
+            return "month";
+        case "d":
+            return "day";
+        case "h":
+            return "hour";
+        case "min":
+            return "minute";
+        case "s":
+            return "second";
+        }
+        return code;
+    }
+
+    public static FHIRPathQuantityValue quantityValue(BigDecimal value, String unit) {
+        return FHIRPathQuantityValue.builder(value, unit).build();
+    }
+
+    @Override
+    public Builder toBuilder() {
+        return new Builder(type, value, unit);
+    }
+    
+    public static Builder builder(BigDecimal value, String unit) {
+        return new Builder(FHIRPathType.SYSTEM_QUANTITY, value, unit);
+    }
+    
+    public static class Builder extends FHIRPathAbstractNode.Builder {
+        private final BigDecimal value;
+        private final String unit;
+        
+        private Builder(FHIRPathType type, BigDecimal value, String unit) {
+            super(type);
+            this.value = value;
+            this.unit = unit;
+        }
+        
+        @Override
+        public Builder name(String name) {
+            return (Builder) super.name(name);
+        }
+        
+        @Override
+        public Builder path(String path) {
+            return (Builder) super.path(path);
+        }
+        
+        @Override
+        public Builder value(FHIRPathSystemValue value) {
+            return this;
+        }
+        
+        @Override
+        public Builder children(FHIRPathNode... children) {
+            return this;
+        }
+        
+        @Override
+        public Builder children(Collection<FHIRPathNode> children) {
+            return this;
+        }
+
+        @Override
+        public FHIRPathQuantityValue build() {
+            return new FHIRPathQuantityValue(this);
+        }
+    }
+    
+    public FHIRPathQuantityValue add(FHIRPathQuantityValue quantityValue) {
+        return FHIRPathQuantityValue.quantityValue(value.add(quantityValue.value()), unit);
+    }
+    
+    public FHIRPathQuantityValue subtract(FHIRPathQuantityValue quantityValue) {
+        return FHIRPathQuantityValue.quantityValue(value.subtract(quantityValue.value()), unit);
+    }
+
+    @Override
+    public boolean isComparableTo(FHIRPathNode other) {
+        if (other instanceof FHIRPathQuantityValue) {
+            return unit.equals(((FHIRPathQuantityValue) other).unit());
+        }
+        if (other.getValue() instanceof FHIRPathQuantityValue) {
+            return unit.equals(((FHIRPathQuantityValue) other.getValue()).unit());
+        }
+        return (other instanceof FHIRPathNumberValue) || (other.getValue() instanceof FHIRPathNumberValue);
+    }
+
+    @Override
+    public int compareTo(FHIRPathNode other) {
+        if (!isComparableTo(other)) {
+            throw new IllegalArgumentException();
+        }
+        if (other instanceof FHIRPathQuantityValue) {
+            return value.compareTo(((FHIRPathQuantityValue) other).value());
+        }
+        return value.compareTo(((FHIRPathQuantityValue) other.getValue()).value());
+    }
+    
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (!(obj instanceof FHIRPathNode)) {
+            return false;
+        }
+        FHIRPathNode other = (FHIRPathNode) obj;
+        if (other instanceof FHIRPathQuantityValue) {
+            return Objects.equals(value, ((FHIRPathQuantityValue) other).value()) && 
+                    Objects.equals(unit, ((FHIRPathQuantityValue) other).unit());
+        }
+        if (other.getValue() instanceof FHIRPathQuantityValue) {
+            return Objects.equals(value, ((FHIRPathQuantityValue) other.getValue()).value()) && 
+                    Objects.equals(unit, ((FHIRPathQuantityValue) other.getValue()).unit());
+        }
+        return false;
+    }
+    
+    @Override
+    public int hashCode() {
+        return Objects.hash(value, unit);
+    }
+    
+    @Override
+    public String toString() {
+        return String.format("%s '%s'", value.toPlainString(), unit);
+    }
+
+    @Override
+    public void accept(FHIRPathNodeVisitor visitor) {
+        visitor.visit(this);
+    }
+}
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathResourceNode.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathResourceNode.java
index 6d1e5274847..ed83c8722cd 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathResourceNode.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathResourceNode.java
@@ -111,7 +111,7 @@ public int hashCode() {
     }
 
     @Override
-    public <T> void accept(T param, FHIRPathNodeVisitor<T> visitor) {
-        visitor.visit(param, this);
+    public void accept(FHIRPathNodeVisitor visitor) {
+        visitor.visit(this);
     }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathStringValue.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathStringValue.java
index 908b82ffcbb..6a83a99a527 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathStringValue.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathStringValue.java
@@ -11,7 +11,7 @@
 
 import com.ibm.fhir.model.path.visitor.FHIRPathNodeVisitor;
 
-public class FHIRPathStringValue extends FHIRPathAbstractNode implements FHIRPathPrimitiveValue {
+public class FHIRPathStringValue extends FHIRPathAbstractNode implements FHIRPathSystemValue {
     public static final FHIRPathStringValue EMPTY_STRING = stringValue("");
     
     private final String string;
@@ -66,7 +66,7 @@ public Builder path(String path) {
         }
         
         @Override
-        public Builder value(FHIRPathPrimitiveValue value) {
+        public Builder value(FHIRPathSystemValue value) {
             return this;
         }
         
@@ -183,7 +183,7 @@ public String toString() {
     }
 
     @Override
-    public <T> void accept(T param, FHIRPathNodeVisitor<T> visitor) {
-        visitor.visit(param, this);
+    public void accept(FHIRPathNodeVisitor visitor) {
+        visitor.visit(this);
     }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathPrimitiveValue.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathSystemValue.java
similarity index 67%
rename from fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathPrimitiveValue.java
rename to fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathSystemValue.java
index 1b244f3f8ba..4f662f8b4b3 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathPrimitiveValue.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathSystemValue.java
@@ -6,43 +6,43 @@
 
 package com.ibm.fhir.model.path;
 
-public interface FHIRPathPrimitiveValue extends FHIRPathNode {
+public interface FHIRPathSystemValue extends FHIRPathNode {
     @Override
     default boolean hasValue() {
         return false;
     }
     @Override
-    default boolean isPrimitiveValue() {
+    default boolean isSystemValue() {
         return true;
     }
     default boolean isBooleanValue() {
         return false;
     }
-    default boolean isDateTimeValue() {
-        return false;
-    }
     default boolean isStringValue() {
         return false;
     }
-    default boolean isTimeValue() {
+    default boolean isQuantityValue() {
         return false;
     }
     default boolean isNumberValue() {
         return false;
     }
+    default boolean isTemporalValue() {
+        return false;
+    }
     default FHIRPathBooleanValue asBooleanValue() {
         return as(FHIRPathBooleanValue.class);
     }
-    default FHIRPathDateTimeValue asDateTimeValue() {
-        return as(FHIRPathDateTimeValue.class);
-    }
     default FHIRPathStringValue asStringValue() {
         return as(FHIRPathStringValue.class);
     }
-    default FHIRPathTimeValue asTimeValue() {
-        return as(FHIRPathTimeValue.class);
+    default FHIRPathQuantityValue asQuantityValue() {
+        return as(FHIRPathQuantityValue.class);
     }
     default FHIRPathNumberValue asNumberValue() {
         return as(FHIRPathNumberValue.class);
     }
+    default FHIRPathTemporalValue asTemporalValue() {
+        return as(FHIRPathTemporalValue.class);
+    }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTemporalValue.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTemporalValue.java
new file mode 100644
index 00000000000..ddd2957f0e3
--- /dev/null
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTemporalValue.java
@@ -0,0 +1,45 @@
+/*
+ * (C) Copyright IBM Corp. 2019
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.ibm.fhir.model.path;
+
+import java.time.temporal.Temporal;
+
+public interface FHIRPathTemporalValue extends FHIRPathSystemValue {
+    @Override
+    default boolean isTemporalValue() {
+        return true;
+    }
+    
+    default boolean isDateValue() {
+        return false;
+    }
+    
+    default boolean isDateTimeValue() {
+        return false;
+    }
+    
+    default boolean isTimeValue() {
+        return false;
+    }
+    
+    Temporal temporal();
+    
+    default FHIRPathDateValue asDateValue() {
+        return as(FHIRPathDateValue.class);
+    }
+    
+    default FHIRPathDateTimeValue asDateTimeValue() {
+        return as(FHIRPathDateTimeValue.class);
+    }
+    
+    default FHIRPathTimeValue asTimeValue() {
+        return as(FHIRPathTimeValue.class);
+    }
+    
+    FHIRPathTemporalValue add(FHIRPathQuantityValue quantityValue);
+    FHIRPathTemporalValue subtract(FHIRPathQuantityValue quantityValue);
+}
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTimeValue.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTimeValue.java
index 14f5452e3f1..38425186c86 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTimeValue.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTimeValue.java
@@ -23,7 +23,7 @@
 
 import com.ibm.fhir.model.path.visitor.FHIRPathNodeVisitor;
 
-public class FHIRPathTimeValue extends FHIRPathAbstractNode implements FHIRPathPrimitiveValue {
+public class FHIRPathTimeValue extends FHIRPathAbstractNode implements FHIRPathTemporalValue {
     private static final DateTimeFormatter TIME_PARSER_FORMATTER = new DateTimeFormatterBuilder()
             .appendPattern("'T'HH:mm:ss")
             .optionalStart()
@@ -35,10 +35,12 @@ public class FHIRPathTimeValue extends FHIRPathAbstractNode implements FHIRPathP
             .toFormatter();
     
     private final TemporalAccessor time;
+    private final Temporal temporal;
     
     protected FHIRPathTimeValue(Builder builder) {
         super(builder);
         time = builder.time;
+        temporal = getTemporal(time);
     }
     
     @Override
@@ -61,6 +63,11 @@ public TemporalAccessor time() {
         return time;
     }
     
+    @Override
+    public Temporal temporal() {
+        return temporal;
+    }
+    
     public static FHIRPathTimeValue timeValue(String time) {
         return FHIRPathTimeValue.builder(TIME_PARSER_FORMATTER.parseBest(time, OffsetTime::from, LocalTime::from)).build();
     }
@@ -101,7 +108,7 @@ public Builder path(String path) {
         }
         
         @Override
-        public Builder value(FHIRPathPrimitiveValue value) {
+        public Builder value(FHIRPathSystemValue value) {
             return this;
         }
         
@@ -121,15 +128,15 @@ public FHIRPathTimeValue build() {
         }
     }
     
-    public FHIRPathTimeValue add(FHIRPathQuantityNode quantityNode) {
+    public FHIRPathTimeValue add(FHIRPathQuantityValue quantityValue) {
         Temporal temporal = getTemporal(time);
-        TemporalAmount temporalAmount = getTemporalAmount(quantityNode);
+        TemporalAmount temporalAmount = getTemporalAmount(quantityValue);
         return timeValue(temporal.plus(temporalAmount));
     }
 
-    public FHIRPathTimeValue subtract(FHIRPathQuantityNode quantityNode) {
+    public FHIRPathTimeValue subtract(FHIRPathQuantityValue quantityValue) {
         Temporal temporal = getTemporal(time);
-        TemporalAmount temporalAmount = getTemporalAmount(quantityNode);
+        TemporalAmount temporalAmount = getTemporalAmount(quantityValue);
         return timeValue(temporal.minus(temporalAmount));
     }
 
@@ -193,7 +200,7 @@ public String toString() {
     }
 
     @Override
-    public <T> void accept(T param, FHIRPathNodeVisitor<T> visitor) {
-        visitor.visit(param, this);
+    public void accept(FHIRPathNodeVisitor visitor) {
+        visitor.visit(this);
     }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTree.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTree.java
index c8610babf50..109962f444d 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTree.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTree.java
@@ -100,7 +100,12 @@ protected void doVisitEnd(String elementName, int elementIndex, Resource resourc
         @Override
         protected void doVisitStart(String elementName, int elementIndex, Element element) {
             if (element instanceof Quantity) {
-                builderStack.push(FHIRPathQuantityNode.builder((Quantity) element).name(elementName));
+                Quantity quantity = (Quantity) element;
+                builderStack.push(FHIRPathQuantityNode.builder(quantity).name(elementName));
+                FHIRPathQuantityValue value = FHIRPathQuantityValue.quantityValue(quantity);
+                if (value != null) {
+                    builderStack.peek().value(value);
+                }
             } else {
                 builderStack.push(FHIRPathElementNode.builder(element).name(elementName));
             }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathType.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathType.java
index 265640c847f..c3067760b9a 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathType.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathType.java
@@ -6,9 +6,6 @@
 
 package com.ibm.fhir.model.path;
 
-import java.math.BigDecimal;
-import java.time.LocalTime;
-import java.time.temporal.TemporalAccessor;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -306,30 +303,34 @@ public enum FHIRPathType {
     
     // FHIRPath system types
     SYSTEM_ANY("System", "Any"),
-    SYSTEM_BOOLEAN("System", "Boolean", SYSTEM_ANY, java.lang.Boolean.class),
-    SYSTEM_STRING("System", "String", SYSTEM_ANY, java.lang.String.class),
-    SYSTEM_INTEGER("System", "Integer", SYSTEM_ANY, java.lang.Integer.class),
-    SYSTEM_DECIMAL("System", "Decimal", SYSTEM_ANY, BigDecimal.class),
-    SYSTEM_DATE_TIME("System", "DateTime", SYSTEM_ANY, TemporalAccessor.class),
-    SYSTEM_TIME("System", "Time", SYSTEM_ANY, LocalTime.class),
+    SYSTEM_BOOLEAN("System", "Boolean", SYSTEM_ANY),
+    SYSTEM_STRING("System", "String", SYSTEM_ANY),
+    SYSTEM_INTEGER("System", "Integer", SYSTEM_ANY),
+    SYSTEM_DECIMAL("System", "Decimal", SYSTEM_ANY),
+    SYSTEM_DATE("System", "Date", SYSTEM_ANY),
+    SYSTEM_DATE_TIME("System", "DateTime", SYSTEM_ANY),
+    SYSTEM_QUANTITY("System", "Quantity", SYSTEM_ANY),
+    SYSTEM_TIME("System", "Time", SYSTEM_ANY),
     
     // FHIRPath metamodel types
-    SYSTEM_TYPE_INFO("System", "TypeInfo", SYSTEM_ANY, TypeInfo.class),
-    SYSTEM_CLASS_INFO("System", "ClassInfo", SYSTEM_TYPE_INFO, ClassInfo.class),
-    SYSTEM_TUPLE_TYPE_INFO("System", "TupleTypeInfo", SYSTEM_TYPE_INFO, TupleTypeInfo.class),
-    SYSTEM_LIST_TYPE_INFO("System", "ListTypeInfo", SYSTEM_TYPE_INFO, ListTypeInfo.class),
-    SYSTEM_SIMPLE_TYPE_INFO("System", "SystemTypeInfo", SYSTEM_TYPE_INFO, SimpleTypeInfo.class);
+    SYSTEM_TYPE_INFO("System", "TypeInfo", SYSTEM_ANY),
+    SYSTEM_CLASS_INFO("System", "ClassInfo", SYSTEM_TYPE_INFO),
+    SYSTEM_TUPLE_TYPE_INFO("System", "TupleTypeInfo", SYSTEM_TYPE_INFO),
+    SYSTEM_LIST_TYPE_INFO("System", "ListTypeInfo", SYSTEM_TYPE_INFO),
+    SYSTEM_SIMPLE_TYPE_INFO("System", "SystemTypeInfo", SYSTEM_TYPE_INFO);
     
     private final java.lang.String namespace;
     private final java.lang.String name;
     private final FHIRPathType baseType;
     private final Class<?> modelClass;
     
-    private static final Map<java.lang.String, FHIRPathType> TYPE_NAME_MAP = createTypeNameMap();
-    private static final Map<Class<?>, FHIRPathType> TYPE_MAP = createTypeMap();
-    private static final Set<FHIRPathType> SYSTEM_TYPES = new HashSet<>(Arrays.asList(SYSTEM_BOOLEAN, SYSTEM_STRING, SYSTEM_INTEGER, SYSTEM_DECIMAL, SYSTEM_DATE_TIME, SYSTEM_TIME));
+    private static final Map<java.lang.String, FHIRPathType> TYPE_NAME_MAP = buildTypeNameMap();
+    private static final Map<Class<?>, FHIRPathType> TYPE_MAP = buildTypeMap();
+    private static final Set<FHIRPathType> SYSTEM_TYPES = new HashSet<>(Arrays.asList(SYSTEM_BOOLEAN, SYSTEM_STRING, SYSTEM_INTEGER, SYSTEM_DECIMAL, SYSTEM_DATE, SYSTEM_DATE_TIME, SYSTEM_QUANTITY, SYSTEM_TIME));
+    private static final Set<FHIRPathType> METAMODEL_TYPES = new HashSet<>(Arrays.asList(SYSTEM_TYPE_INFO, SYSTEM_CLASS_INFO, SYSTEM_TUPLE_TYPE_INFO, SYSTEM_LIST_TYPE_INFO, SYSTEM_SIMPLE_TYPE_INFO));
+    private static final Map<Class<?>, FHIRPathType> METAMODEL_TYPE_MAP = buildMetamodelTypeMap();
     
-    private static Map<java.lang.String, FHIRPathType> createTypeNameMap() {
+    private static Map<java.lang.String, FHIRPathType> buildTypeNameMap() {
         Map<java.lang.String, FHIRPathType> typeNameMap = new HashMap<>();
         for (FHIRPathType type : FHIRPathType.values()) {
             typeNameMap.put(type.namespace + "." + type.name, type);
@@ -337,11 +338,21 @@ private static Map<java.lang.String, FHIRPathType> createTypeNameMap() {
         return typeNameMap;
     }
 
-    private static Map<Class<?>, FHIRPathType> createTypeMap() {
+    private static Map<Class<?>, FHIRPathType> buildMetamodelTypeMap() {
+        Map<Class<?>, FHIRPathType> metamodelTypeMap = new HashMap<>();
+        metamodelTypeMap.put(TypeInfo.class, SYSTEM_TYPE_INFO);
+        metamodelTypeMap.put(ClassInfo.class, SYSTEM_CLASS_INFO);
+        metamodelTypeMap.put(TupleTypeInfo.class, SYSTEM_TUPLE_TYPE_INFO);
+        metamodelTypeMap.put(ListTypeInfo.class, SYSTEM_LIST_TYPE_INFO);
+        metamodelTypeMap.put(SimpleTypeInfo.class, SYSTEM_SIMPLE_TYPE_INFO);
+        return metamodelTypeMap;
+    }
+
+    private static Map<Class<?>, FHIRPathType> buildTypeMap() {
         Map<Class<?>, FHIRPathType> typeMap = new HashMap<>();
         for (FHIRPathType type : FHIRPathType.values()) {
             if (type.modelClass != null) {
-              typeMap.put(type.modelClass, type);
+                typeMap.put(type.modelClass, type);
             }
         }
         return typeMap;
@@ -350,6 +361,10 @@ private static Map<Class<?>, FHIRPathType> createTypeMap() {
     FHIRPathType(java.lang.String namespace, java.lang.String name) {
         this(namespace, name, null, null);
     }
+    
+    FHIRPathType(java.lang.String namespace, java.lang.String name, FHIRPathType baseType) {
+        this(namespace, name, baseType, null);
+    }
   
     FHIRPathType(java.lang.String namespace, java.lang.String name, FHIRPathType baseType, Class<?> modelClass) {
         this.namespace = namespace;
@@ -421,16 +436,22 @@ public static FHIRPathType from(java.lang.String namespace, java.lang.String nam
         return TYPE_NAME_MAP.get(namespace + "." + name);
     }
     
-    public static FHIRPathType from(Class<?> modelClass) {
-        FHIRPathType type = TYPE_MAP.get(ModelSupport.getConcreteType(modelClass));
-        if (type == null) {
-            if (BackboneElement.class.isAssignableFrom(modelClass)) {
-                type = FHIR_BACKBONE_ELEMENT;
-            } else if (Code.class.isAssignableFrom(modelClass)) {
-                type = FHIR_CODE;
+    public static FHIRPathType from(Class<?> clazz) {
+        if (TypeInfo.class.isAssignableFrom(clazz)) {
+            return METAMODEL_TYPE_MAP.get(clazz);
+        }
+        if (ModelSupport.isModelClass(clazz)) {
+            FHIRPathType type = TYPE_MAP.get(ModelSupport.getConcreteType(clazz));
+            if (type == null) {
+                if (BackboneElement.class.isAssignableFrom(clazz)) {
+                    type = FHIR_BACKBONE_ELEMENT;
+                } else if (Code.class.isAssignableFrom(clazz)) {
+                    type = FHIR_CODE;
+                }
             }
+            return type;
         }
-        return type;
+        return null;
     }
     
     public static Set<FHIRPathType> getSystemTypes() {
@@ -440,4 +461,12 @@ public static Set<FHIRPathType> getSystemTypes() {
     public static boolean isSystemType(FHIRPathType type) {
         return SYSTEM_TYPES.contains(type);
     }
+    
+    public static Set<FHIRPathType> getMetamodelTypes() {
+        return METAMODEL_TYPES;
+    }
+    
+    public static boolean isMetamodelType(FHIRPathType type) {
+        return METAMODEL_TYPES.contains(type);
+    }
 }
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTypeInfoNode.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTypeInfoNode.java
index 0db3ee29ddf..921c185651d 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTypeInfoNode.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathTypeInfoNode.java
@@ -46,8 +46,8 @@ public FHIRPathTypeInfoNode build() {
     }
 
     @Override
-    public <T> void accept(T param, FHIRPathNodeVisitor<T> visitor) {
-        visitor.visit(param, this);
+    public void accept(FHIRPathNodeVisitor visitor) {
+        visitor.visit(this);
     }
 
     @Override
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathVisitor.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathVisitor.java
index 4b6f5669d98..31e1de1202c 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathVisitor.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/FHIRPathVisitor.java
@@ -1,396 +1,290 @@
-/*
- * (C) Copyright IBM Corp. 2019
- *
- * SPDX-License-Identifier: Apache-2.0
- */
-
+// Generated from FHIRPath.g4 by ANTLR 4.7.2
 package com.ibm.fhir.model.path;
-
 import org.antlr.v4.runtime.tree.ParseTreeVisitor;
 
 /**
- * This interface defines a complete generic visitor for a parse tree produced by {@link FHIRPathParser}.
+ * This interface defines a complete generic visitor for a parse tree produced
+ * by {@link FHIRPathParser}.
  *
- * @param <T>
- *            The return type of the visit operation. Use {@link Void} for operations with no return type.
+ * @param <T> The return type of the visit operation. Use {@link Void} for
+ * operations with no return type.
  */
 public interface FHIRPathVisitor<T> extends ParseTreeVisitor<T> {
     /**
-     * Visit a parse tree produced by the {@code indexerExpression} labeled alternative in
-     * {@link FHIRPathParser#expression}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code indexerExpression}
+     * labeled alternative in {@link FHIRPathParser#expression}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitIndexerExpression(FHIRPathParser.IndexerExpressionContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code polarityExpression} labeled alternative in
-     * {@link FHIRPathParser#expression}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code polarityExpression}
+     * labeled alternative in {@link FHIRPathParser#expression}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitPolarityExpression(FHIRPathParser.PolarityExpressionContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code additiveExpression} labeled alternative in
-     * {@link FHIRPathParser#expression}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code additiveExpression}
+     * labeled alternative in {@link FHIRPathParser#expression}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitAdditiveExpression(FHIRPathParser.AdditiveExpressionContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code multiplicativeExpression} labeled alternative in
-     * {@link FHIRPathParser#expression}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code multiplicativeExpression}
+     * labeled alternative in {@link FHIRPathParser#expression}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitMultiplicativeExpression(FHIRPathParser.MultiplicativeExpressionContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code unionExpression} labeled alternative in
-     * {@link FHIRPathParser#expression}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code unionExpression}
+     * labeled alternative in {@link FHIRPathParser#expression}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitUnionExpression(FHIRPathParser.UnionExpressionContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code orExpression} labeled alternative in {@link FHIRPathParser#expression}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code orExpression}
+     * labeled alternative in {@link FHIRPathParser#expression}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitOrExpression(FHIRPathParser.OrExpressionContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code andExpression} labeled alternative in
-     * {@link FHIRPathParser#expression}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code andExpression}
+     * labeled alternative in {@link FHIRPathParser#expression}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitAndExpression(FHIRPathParser.AndExpressionContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code membershipExpression} labeled alternative in
-     * {@link FHIRPathParser#expression}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code membershipExpression}
+     * labeled alternative in {@link FHIRPathParser#expression}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitMembershipExpression(FHIRPathParser.MembershipExpressionContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code inequalityExpression} labeled alternative in
-     * {@link FHIRPathParser#expression}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code inequalityExpression}
+     * labeled alternative in {@link FHIRPathParser#expression}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitInequalityExpression(FHIRPathParser.InequalityExpressionContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code invocationExpression} labeled alternative in
-     * {@link FHIRPathParser#expression}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code invocationExpression}
+     * labeled alternative in {@link FHIRPathParser#expression}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitInvocationExpression(FHIRPathParser.InvocationExpressionContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code equalityExpression} labeled alternative in
-     * {@link FHIRPathParser#expression}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code equalityExpression}
+     * labeled alternative in {@link FHIRPathParser#expression}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitEqualityExpression(FHIRPathParser.EqualityExpressionContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code impliesExpression} labeled alternative in
-     * {@link FHIRPathParser#expression}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code impliesExpression}
+     * labeled alternative in {@link FHIRPathParser#expression}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitImpliesExpression(FHIRPathParser.ImpliesExpressionContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code termExpression} labeled alternative in
-     * {@link FHIRPathParser#expression}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code termExpression}
+     * labeled alternative in {@link FHIRPathParser#expression}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitTermExpression(FHIRPathParser.TermExpressionContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code typeExpression} labeled alternative in
-     * {@link FHIRPathParser#expression}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code typeExpression}
+     * labeled alternative in {@link FHIRPathParser#expression}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitTypeExpression(FHIRPathParser.TypeExpressionContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code invocationTerm} labeled alternative in {@link FHIRPathParser#term}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code invocationTerm}
+     * labeled alternative in {@link FHIRPathParser#term}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitInvocationTerm(FHIRPathParser.InvocationTermContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code literalTerm} labeled alternative in {@link FHIRPathParser#term}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code literalTerm}
+     * labeled alternative in {@link FHIRPathParser#term}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitLiteralTerm(FHIRPathParser.LiteralTermContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code externalConstantTerm} labeled alternative in
-     * {@link FHIRPathParser#term}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code externalConstantTerm}
+     * labeled alternative in {@link FHIRPathParser#term}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitExternalConstantTerm(FHIRPathParser.ExternalConstantTermContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code parenthesizedTerm} labeled alternative in {@link FHIRPathParser#term}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code parenthesizedTerm}
+     * labeled alternative in {@link FHIRPathParser#term}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitParenthesizedTerm(FHIRPathParser.ParenthesizedTermContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code nullLiteral} labeled alternative in {@link FHIRPathParser#literal}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code nullLiteral}
+     * labeled alternative in {@link FHIRPathParser#literal}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitNullLiteral(FHIRPathParser.NullLiteralContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code booleanLiteral} labeled alternative in {@link FHIRPathParser#literal}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code booleanLiteral}
+     * labeled alternative in {@link FHIRPathParser#literal}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitBooleanLiteral(FHIRPathParser.BooleanLiteralContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code stringLiteral} labeled alternative in {@link FHIRPathParser#literal}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code stringLiteral}
+     * labeled alternative in {@link FHIRPathParser#literal}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitStringLiteral(FHIRPathParser.StringLiteralContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code numberLiteral} labeled alternative in {@link FHIRPathParser#literal}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code numberLiteral}
+     * labeled alternative in {@link FHIRPathParser#literal}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitNumberLiteral(FHIRPathParser.NumberLiteralContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code dateTimeLiteral} labeled alternative in {@link FHIRPathParser#literal}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code dateLiteral}
+     * labeled alternative in {@link FHIRPathParser#literal}.
+     * @param ctx the parse tree
+     * @return the visitor result
+     */
+    T visitDateLiteral(FHIRPathParser.DateLiteralContext ctx);
+    /**
+     * Visit a parse tree produced by the {@code dateTimeLiteral}
+     * labeled alternative in {@link FHIRPathParser#literal}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitDateTimeLiteral(FHIRPathParser.DateTimeLiteralContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code timeLiteral} labeled alternative in {@link FHIRPathParser#literal}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code timeLiteral}
+     * labeled alternative in {@link FHIRPathParser#literal}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitTimeLiteral(FHIRPathParser.TimeLiteralContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code quantityLiteral} labeled alternative in {@link FHIRPathParser#literal}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code quantityLiteral}
+     * labeled alternative in {@link FHIRPathParser#literal}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitQuantityLiteral(FHIRPathParser.QuantityLiteralContext ctx);
-
     /**
      * Visit a parse tree produced by {@link FHIRPathParser#externalConstant}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitExternalConstant(FHIRPathParser.ExternalConstantContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code memberInvocation} labeled alternative in
-     * {@link FHIRPathParser#invocation}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code memberInvocation}
+     * labeled alternative in {@link FHIRPathParser#invocation}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitMemberInvocation(FHIRPathParser.MemberInvocationContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code functionInvocation} labeled alternative in
-     * {@link FHIRPathParser#invocation}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code functionInvocation}
+     * labeled alternative in {@link FHIRPathParser#invocation}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitFunctionInvocation(FHIRPathParser.FunctionInvocationContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code thisInvocation} labeled alternative in
-     * {@link FHIRPathParser#invocation}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code thisInvocation}
+     * labeled alternative in {@link FHIRPathParser#invocation}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitThisInvocation(FHIRPathParser.ThisInvocationContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code indexInvocation} labeled alternative in
-     * {@link FHIRPathParser#invocation}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code indexInvocation}
+     * labeled alternative in {@link FHIRPathParser#invocation}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitIndexInvocation(FHIRPathParser.IndexInvocationContext ctx);
-
     /**
-     * Visit a parse tree produced by the {@code totalInvocation} labeled alternative in
-     * {@link FHIRPathParser#invocation}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * Visit a parse tree produced by the {@code totalInvocation}
+     * labeled alternative in {@link FHIRPathParser#invocation}.
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitTotalInvocation(FHIRPathParser.TotalInvocationContext ctx);
-
     /**
      * Visit a parse tree produced by {@link FHIRPathParser#function}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitFunction(FHIRPathParser.FunctionContext ctx);
-
     /**
      * Visit a parse tree produced by {@link FHIRPathParser#paramList}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitParamList(FHIRPathParser.ParamListContext ctx);
-
     /**
      * Visit a parse tree produced by {@link FHIRPathParser#quantity}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitQuantity(FHIRPathParser.QuantityContext ctx);
-
     /**
      * Visit a parse tree produced by {@link FHIRPathParser#unit}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitUnit(FHIRPathParser.UnitContext ctx);
-
     /**
      * Visit a parse tree produced by {@link FHIRPathParser#dateTimePrecision}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitDateTimePrecision(FHIRPathParser.DateTimePrecisionContext ctx);
-
     /**
      * Visit a parse tree produced by {@link FHIRPathParser#pluralDateTimePrecision}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitPluralDateTimePrecision(FHIRPathParser.PluralDateTimePrecisionContext ctx);
-
     /**
      * Visit a parse tree produced by {@link FHIRPathParser#typeSpecifier}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitTypeSpecifier(FHIRPathParser.TypeSpecifierContext ctx);
-
     /**
      * Visit a parse tree produced by {@link FHIRPathParser#qualifiedIdentifier}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitQualifiedIdentifier(FHIRPathParser.QualifiedIdentifierContext ctx);
-
     /**
      * Visit a parse tree produced by {@link FHIRPathParser#identifier}.
-     * 
-     * @param ctx
-     *            the parse tree
+     * @param ctx the parse tree
      * @return the visitor result
      */
     T visitIdentifier(FHIRPathParser.IdentifierContext ctx);
-}
+}
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/evaluator/FHIRPathEvaluator.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/evaluator/FHIRPathEvaluator.java
index cc4a4416b68..1981e5a6c5e 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/evaluator/FHIRPathEvaluator.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/evaluator/FHIRPathEvaluator.java
@@ -14,16 +14,20 @@
 import static com.ibm.fhir.model.path.util.FHIRPathUtil.empty;
 import static com.ibm.fhir.model.path.util.FHIRPathUtil.evaluatesToBoolean;
 import static com.ibm.fhir.model.path.util.FHIRPathUtil.getInteger;
-import static com.ibm.fhir.model.path.util.FHIRPathUtil.getPrimitiveValue;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.getQuantityNode;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.getQuantityValue;
 import static com.ibm.fhir.model.path.util.FHIRPathUtil.getSingleton;
 import static com.ibm.fhir.model.path.util.FHIRPathUtil.getString;
-import static com.ibm.fhir.model.path.util.FHIRPathUtil.hasPrimitiveValue;
-import static com.ibm.fhir.model.path.util.FHIRPathUtil.hasValueAndUnit;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.getSystemValue;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.getTemporalValue;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.hasQuantityNode;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.hasQuantityValue;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.hasSystemValue;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.hasTemporalValue;
 import static com.ibm.fhir.model.path.util.FHIRPathUtil.isFalse;
 import static com.ibm.fhir.model.path.util.FHIRPathUtil.isSingleton;
 import static com.ibm.fhir.model.path.util.FHIRPathUtil.isTrue;
 import static com.ibm.fhir.model.path.util.FHIRPathUtil.singleton;
-import static com.ibm.fhir.model.type.String.string;
 
 import java.math.BigDecimal;
 import java.util.ArrayList;
@@ -38,29 +42,30 @@
 import java.util.Stack;
 import java.util.stream.Collectors;
 
-import org.antlr.v4.runtime.ANTLRInputStream;
+import org.antlr.v4.runtime.CharStreams;
 import org.antlr.v4.runtime.CommonTokenStream;
 import org.antlr.v4.runtime.tree.ParseTree;
 
 import com.ibm.fhir.model.path.FHIRPathBaseVisitor;
 import com.ibm.fhir.model.path.FHIRPathBooleanValue;
 import com.ibm.fhir.model.path.FHIRPathDateTimeValue;
+import com.ibm.fhir.model.path.FHIRPathDateValue;
 import com.ibm.fhir.model.path.FHIRPathLexer;
 import com.ibm.fhir.model.path.FHIRPathNode;
 import com.ibm.fhir.model.path.FHIRPathParser;
 import com.ibm.fhir.model.path.FHIRPathParser.ExpressionContext;
 import com.ibm.fhir.model.path.FHIRPathParser.ParamListContext;
-import com.ibm.fhir.model.path.FHIRPathPrimitiveValue;
 import com.ibm.fhir.model.path.FHIRPathQuantityNode;
+import com.ibm.fhir.model.path.FHIRPathQuantityValue;
+import com.ibm.fhir.model.path.FHIRPathSystemValue;
+import com.ibm.fhir.model.path.FHIRPathTemporalValue;
 import com.ibm.fhir.model.path.FHIRPathTimeValue;
 import com.ibm.fhir.model.path.FHIRPathTree;
 import com.ibm.fhir.model.path.FHIRPathType;
 import com.ibm.fhir.model.path.exception.FHIRPathException;
 import com.ibm.fhir.model.path.function.FHIRPathFunction;
 import com.ibm.fhir.model.resource.Resource;
-import com.ibm.fhir.model.type.Decimal;
 import com.ibm.fhir.model.type.Element;
-import com.ibm.fhir.model.type.Quantity;
 
 public class FHIRPathEvaluator {
     public static boolean DEBUG = false;
@@ -115,7 +120,7 @@ private static ExpressionContext getExpressionContext(String expr) {
     }
     
     private static ExpressionContext compile(String expr) {
-        FHIRPathLexer lexer = new FHIRPathLexer(new ANTLRInputStream(expr));
+        FHIRPathLexer lexer = new FHIRPathLexer(CharStreams.fromString(expr));
         CommonTokenStream tokens = new CommonTokenStream(lexer);
         FHIRPathParser parser = new FHIRPathParser(tokens);
         return parser.expression();
@@ -351,10 +356,7 @@ private Collection<FHIRPathNode> where(List<ExpressionContext> arguments) {
             }
             return result;
         }
-
-        /**
-         * expression '[' expression ']'
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitIndexerExpression(FHIRPathParser.IndexerExpressionContext ctx) {
             debug(ctx);
@@ -375,9 +377,6 @@ public Collection<FHIRPathNode> visitIndexerExpression(FHIRPathParser.IndexerExp
             return result;
         }
         
-        /**
-         * ('+' | '-') expression
-         */
         @Override
         public Collection<FHIRPathNode> visitPolarityExpression(FHIRPathParser.PolarityExpressionContext ctx) {
             debug(ctx);
@@ -392,7 +391,7 @@ public Collection<FHIRPathNode> visitPolarityExpression(FHIRPathParser.PolarityE
             
             Collection<FHIRPathNode> result = empty();
             
-            FHIRPathPrimitiveValue value = getPrimitiveValue(nodes);
+            FHIRPathSystemValue value = getSystemValue(nodes);
             String polarity = ctx.getChild(0).getText();
             
             if (value.isNumberValue()) {
@@ -410,9 +409,6 @@ public Collection<FHIRPathNode> visitPolarityExpression(FHIRPathParser.PolarityE
             return result;
         }
         
-        /**
-         * expression ('+' | '-' | '&') expression
-         */
         @Override
         public Collection<FHIRPathNode> visitAdditiveExpression(FHIRPathParser.AdditiveExpressionContext ctx) {
             debug(ctx);
@@ -425,10 +421,9 @@ public Collection<FHIRPathNode> visitAdditiveExpression(FHIRPathParser.AdditiveE
             
             String operator = ctx.getChild(1).getText();
             
-            if (hasPrimitiveValue(left) && hasPrimitiveValue(right)) {
-                FHIRPathPrimitiveValue leftValue = getPrimitiveValue(left);
-                FHIRPathPrimitiveValue rightValue = getPrimitiveValue(right);
-                
+            if (hasSystemValue(left) && hasSystemValue(right)) {
+                FHIRPathSystemValue leftValue = getSystemValue(left);
+                FHIRPathSystemValue rightValue = getSystemValue(right);
                 if (leftValue.isNumberValue() && rightValue.isNumberValue()) {            
                     switch (operator) {
                     case "+":
@@ -442,105 +437,61 @@ public Collection<FHIRPathNode> visitAdditiveExpression(FHIRPathParser.AdditiveE
                     // concatenation
                     result = singleton(leftValue.asStringValue().concat(rightValue.asStringValue()));
                 }
-            } else if (((hasPrimitiveValue(left) && right.isEmpty()) || (left.isEmpty() && hasPrimitiveValue(right))) && "&".equals(operator)) {
+            } else if (((hasSystemValue(left) && right.isEmpty()) || (left.isEmpty() && hasSystemValue(right))) && "&".equals(operator)) {
                 // concatenation where an empty collection is treated as an empty string
-                if (hasPrimitiveValue(left) && right.isEmpty()) {
-                    FHIRPathPrimitiveValue leftValue = getPrimitiveValue(left);
+                if (hasSystemValue(left) && right.isEmpty()) {
+                    FHIRPathSystemValue leftValue = getSystemValue(left);
                     if (leftValue.isStringValue()) {
                         result = singleton(leftValue.asStringValue().concat(EMPTY_STRING));
                     }
-                } else if (left.isEmpty() && hasPrimitiveValue(right)) {
-                    FHIRPathPrimitiveValue rightValue = getPrimitiveValue(right);
+                } else if (left.isEmpty() && hasSystemValue(right)) {
+                    FHIRPathSystemValue rightValue = getSystemValue(right);
                     if (rightValue.isStringValue()) {
                         result = singleton(EMPTY_STRING.concat(rightValue.asStringValue()));
                     }
                 } else if (left.isEmpty() && right.isEmpty()) {
                     result = singleton(EMPTY_STRING);
                 }
-            } else if (isSingleton(left) && isSingleton(right)) {
-                FHIRPathNode leftNode = getSingleton(left);
-                FHIRPathNode rightNode = getSingleton(right);
-                
-                if (leftNode instanceof FHIRPathQuantityNode && rightNode instanceof FHIRPathQuantityNode) {
-                    FHIRPathQuantityNode leftQuantity = (FHIRPathQuantityNode) leftNode;
-                    FHIRPathQuantityNode rightQuantity = (FHIRPathQuantityNode) rightNode;
-                    
-                    if (hasValueAndUnit(leftQuantity) && hasValueAndUnit(rightQuantity) && 
-                            // units are the same
-                            leftQuantity.getQuantityUnit().equals(rightQuantity.getQuantityUnit())) {
-                        switch (operator) {
-                        case "+":
-                            result = singleton(leftQuantity.add(rightQuantity));
-                            break;
-                        case "-":
-                            result = singleton(leftQuantity.subtract(rightQuantity));
-                            break;
-                        }
-                    }
-                } else if ((leftNode instanceof FHIRPathDateTimeValue && rightNode instanceof FHIRPathQuantityNode) || 
-                        (leftNode instanceof FHIRPathQuantityNode && rightNode instanceof FHIRPathDateTimeValue)) {
-                    
-                    FHIRPathDateTimeValue dateTimeValue;
-                    if (leftNode instanceof FHIRPathDateTimeValue) {
-                        dateTimeValue = (FHIRPathDateTimeValue) leftNode;
-                    } else {
-                        dateTimeValue = (FHIRPathDateTimeValue) rightNode;
-                    }
-                    
-                    FHIRPathQuantityNode quantityNode;
-                    if (leftNode instanceof FHIRPathQuantityNode) {
-                        quantityNode = (FHIRPathQuantityNode) leftNode;
-                    } else {
-                        quantityNode = (FHIRPathQuantityNode) rightNode;
-                    }
-                    
-                    if (hasValueAndUnit(quantityNode)) {
-                        switch (operator) {
-                        case "+":
-                            result = singleton(dateTimeValue.add(quantityNode));
-                            break;
-                        case "-":
-                            result = singleton(dateTimeValue.subtract(quantityNode));
-                            break;
-                        }
-                    }
-                } else if ((leftNode instanceof FHIRPathTimeValue && rightNode instanceof FHIRPathQuantityNode) || 
-                        (leftNode instanceof FHIRPathQuantityNode && rightNode instanceof FHIRPathTimeValue)) {
-                    
-                    FHIRPathTimeValue timeValue;
-                    if (leftNode instanceof FHIRPathTimeValue) {
-                        timeValue = (FHIRPathTimeValue) leftNode;
-                    } else {
-                        timeValue = (FHIRPathTimeValue) rightNode;
-                    }
-                    
-                    FHIRPathQuantityNode quantityNode;
-                    if (leftNode instanceof FHIRPathQuantityNode) {
-                        quantityNode = (FHIRPathQuantityNode) leftNode;
-                    } else {
-                        quantityNode = (FHIRPathQuantityNode) rightNode;
-                    }
-                    
-                    if (hasValueAndUnit(quantityNode)) {
-                        switch (operator) {
-                        case "+":
-                            result = singleton(timeValue.add(quantityNode));
-                            break;
-                        case "-":
-                            result = singleton(timeValue.subtract(quantityNode));
-                            break;
-                        }
-                    }
+            } else if (hasQuantityValue(left) && hasQuantityValue(right)) {
+                FHIRPathQuantityValue leftValue = getQuantityValue(left);
+                FHIRPathQuantityValue rightValue = getQuantityValue(right);
+                switch (operator) {
+                case "+":
+                    result = singleton(leftValue.add(rightValue));
+                    break;
+                case "-":
+                    result = singleton(leftValue.subtract(rightValue));
+                    break;
+                }
+            } else if ((hasTemporalValue(left) && hasQuantityValue(right)) || 
+                    (hasQuantityValue(left) && hasTemporalValue(right))) {
+                FHIRPathTemporalValue temporalValue = hasTemporalValue(left) ? getTemporalValue(left) : getTemporalValue(right);
+                FHIRPathQuantityValue quantityValue = hasQuantityValue(left) ? getQuantityValue(left) : getQuantityValue(right);
+                switch (operator) {
+                case "+":
+                    result = singleton(temporalValue.add(quantityValue));
+                    break;
+                case "-":
+                    result = singleton(temporalValue.subtract(quantityValue));
+                    break;
+                }
+            } else if (hasQuantityNode(left) && hasQuantityNode(right)) {
+                FHIRPathQuantityNode leftNode = getQuantityNode(left);
+                FHIRPathQuantityNode rightNode = getQuantityNode(right);
+                switch(operator) {
+                case "+":
+                    result = singleton(leftNode.add(rightNode));
+                    break;
+                case "-":
+                    result = singleton(leftNode.subtract(rightNode));
+                    break;
                 }
             }
                                     
             indentLevel--;
             return result;
         }
-    
-        /**
-         * expression ('*' | '/' | 'div' | 'mod') expression
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitMultiplicativeExpression(FHIRPathParser.MultiplicativeExpressionContext ctx) {
             debug(ctx);
@@ -549,15 +500,15 @@ public Collection<FHIRPathNode> visitMultiplicativeExpression(FHIRPathParser.Mul
             Collection<FHIRPathNode> left = visit(ctx.expression(0));
             Collection<FHIRPathNode> right = visit(ctx.expression(1));
             
-            if (!hasPrimitiveValue(left) || !hasPrimitiveValue(right)) {
+            if (!hasSystemValue(left) || !hasSystemValue(right)) {
                 indentLevel--;
                 return empty();
             }
             
             Collection<FHIRPathNode> result = empty();
             
-            FHIRPathPrimitiveValue leftValue = getPrimitiveValue(left);
-            FHIRPathPrimitiveValue rightValue = getPrimitiveValue(right);
+            FHIRPathSystemValue leftValue = getSystemValue(left);
+            FHIRPathSystemValue rightValue = getSystemValue(right);
             
             String operator = ctx.getChild(1).getText();
 
@@ -586,10 +537,7 @@ public Collection<FHIRPathNode> visitMultiplicativeExpression(FHIRPathParser.Mul
             indentLevel--;
             return result;
         }
-    
-        /**
-         * expression '|' expression
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitUnionExpression(FHIRPathParser.UnionExpressionContext ctx) {
             debug(ctx);
@@ -605,10 +553,7 @@ public Collection<FHIRPathNode> visitUnionExpression(FHIRPathParser.UnionExpress
 //          return union;
             return new ArrayList<>(union);
         }
-    
-        /**
-         * expression ('or' | 'xor') expression
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitOrExpression(FHIRPathParser.OrExpressionContext ctx) {
             debug(ctx);
@@ -662,10 +607,7 @@ public Collection<FHIRPathNode> visitOrExpression(FHIRPathParser.OrExpressionCon
             indentLevel--;
             return result;
         }
-    
-        /**
-         * expression 'and' expression
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitAndExpression(FHIRPathParser.AndExpressionContext ctx) {
             debug(ctx);
@@ -704,10 +646,7 @@ public Collection<FHIRPathNode> visitAndExpression(FHIRPathParser.AndExpressionC
             indentLevel--;
             return result;
         }
-    
-        /**
-         * expression ('in' | 'contains') expression
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitMembershipExpression(FHIRPathParser.MembershipExpressionContext ctx) {
             debug(ctx);
@@ -736,10 +675,7 @@ public Collection<FHIRPathNode> visitMembershipExpression(FHIRPathParser.Members
             indentLevel--;
             return result;
         }
-    
-        /**
-         * expression ('<=' | '<' | '>' | '>=') expression
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitInequalityExpression(FHIRPathParser.InequalityExpressionContext ctx) {
             debug(ctx);
@@ -788,10 +724,7 @@ public Collection<FHIRPathNode> visitInequalityExpression(FHIRPathParser.Inequal
             indentLevel--;
             return result;
         }
-    
-        /**
-         * expression '.' invocation
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitInvocationExpression(FHIRPathParser.InvocationExpressionContext ctx) {
             debug(ctx);
@@ -804,10 +737,7 @@ public Collection<FHIRPathNode> visitInvocationExpression(FHIRPathParser.Invocat
             indentLevel--;
             return result;
         }
-    
-        /**
-         * expression ('=' | '~' | '!=' | '!~') expression
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitEqualityExpression(FHIRPathParser.EqualityExpressionContext ctx) {
             debug(ctx);
@@ -844,10 +774,7 @@ public Collection<FHIRPathNode> visitEqualityExpression(FHIRPathParser.EqualityE
             indentLevel--;
             return result;
         }
-    
-        /**
-         * expression 'implies' expression
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitImpliesExpression(FHIRPathParser.ImpliesExpressionContext ctx) {
             debug(ctx);
@@ -870,9 +797,6 @@ public Collection<FHIRPathNode> visitImpliesExpression(FHIRPathParser.ImpliesExp
             return result;
         }
         
-        /**
-         * term
-         */
         @Override
         public Collection<FHIRPathNode> visitTermExpression(FHIRPathParser.TermExpressionContext ctx) {
             debug(ctx);
@@ -881,10 +805,7 @@ public Collection<FHIRPathNode> visitTermExpression(FHIRPathParser.TermExpressio
             indentLevel--;
             return result;
         }
-    
-        /**
-         * expression ('is' | 'as') typeSpecifier
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitTypeExpression(FHIRPathParser.TypeExpressionContext ctx) {
             debug(ctx);
@@ -925,10 +846,7 @@ public Collection<FHIRPathNode> visitTypeExpression(FHIRPathParser.TypeExpressio
             indentLevel--;
             return Collections.unmodifiableCollection(result);
         }
-
-        /**
-         * invocation
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitInvocationTerm(FHIRPathParser.InvocationTermContext ctx) {
             debug(ctx);
@@ -937,10 +855,7 @@ public Collection<FHIRPathNode> visitInvocationTerm(FHIRPathParser.InvocationTer
             indentLevel--;
             return result;
         }
-    
-        /**
-         * literal
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitLiteralTerm(FHIRPathParser.LiteralTermContext ctx) {
             debug(ctx);
@@ -949,10 +864,7 @@ public Collection<FHIRPathNode> visitLiteralTerm(FHIRPathParser.LiteralTermConte
             indentLevel--;
             return result;
         }
-    
-        /**
-         * externalConstant
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitExternalConstantTerm(FHIRPathParser.ExternalConstantTermContext ctx) {
             debug(ctx);
@@ -961,10 +873,7 @@ public Collection<FHIRPathNode> visitExternalConstantTerm(FHIRPathParser.Externa
             indentLevel--;
             return result;
         }
-    
-        /**
-         * '(' expression ')'
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitParenthesizedTerm(FHIRPathParser.ParenthesizedTermContext ctx) {
             debug(ctx);
@@ -973,39 +882,27 @@ public Collection<FHIRPathNode> visitParenthesizedTerm(FHIRPathParser.Parenthesi
             indentLevel--;
             return result;
         }
-    
-        /**
-         * '{' '}'
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitNullLiteral(FHIRPathParser.NullLiteralContext ctx) {
             debug(ctx);
             return empty();
         }
-    
-        /**
-         * ('true' | 'false')
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitBooleanLiteral(FHIRPathParser.BooleanLiteralContext ctx) {
             debug(ctx);
             Boolean _boolean = Boolean.valueOf(ctx.getText());
             return _boolean ? SINGLETON_TRUE : SINGLETON_FALSE;
         }
-    
-        /**
-         * '\'' (ESC | .)*? '\''
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitStringLiteral(FHIRPathParser.StringLiteralContext ctx) {
             debug(ctx);
             String text = ctx.getText();
             return singleton(stringValue(text.substring(1, text.length() - 1)));
         }
-    
-        /**
-         * [0-9]+('.' [0-9]+)?
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitNumberLiteral(FHIRPathParser.NumberLiteralContext ctx) {
             debug(ctx);
@@ -1018,40 +915,25 @@ public Collection<FHIRPathNode> visitNumberLiteral(FHIRPathParser.NumberLiteralC
                 return singleton(decimalValue(decimal));
             }
         }
-    
-        /**
-         * '@'
-         *  [0-9][0-9][0-9][0-9] // year
-         *  (
-         *      '-'[0-9][0-9] // month
-         *      (
-         *          '-'[0-9][0-9] // day
-         *          (
-         *              'T' TIMEFORMAT
-         *          )?
-         *       )?
-         *   )?
-         *   'Z'? // UTC specifier
-         */
+        
+        @Override
+        public Collection<FHIRPathNode> visitDateLiteral(FHIRPathParser.DateLiteralContext ctx) {
+            debug(ctx);
+            return singleton(FHIRPathDateValue.dateValue(ctx.getText().substring(1)));
+        }
+        
         @Override
         public Collection<FHIRPathNode> visitDateTimeLiteral(FHIRPathParser.DateTimeLiteralContext ctx) {
             debug(ctx);
             return singleton(FHIRPathDateTimeValue.dateTimeValue(ctx.getText().substring(1)));
         }
-    
-        /**
-         * [0-9][0-9] (':'[0-9][0-9] (':'[0-9][0-9] ('.'[0-9]+)?)?)?
-         * ('Z' | ('+' | '-') [0-9][0-9]':'[0-9][0-9])? // timezone
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitTimeLiteral(FHIRPathParser.TimeLiteralContext ctx) {
             debug(ctx);
             return singleton(FHIRPathTimeValue.timeValue(ctx.getText().substring(1)));
         }
-    
-        /**
-         * NUMBER unit?
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitQuantityLiteral(FHIRPathParser.QuantityLiteralContext ctx) {
             debug(ctx);
@@ -1060,10 +942,7 @@ public Collection<FHIRPathNode> visitQuantityLiteral(FHIRPathParser.QuantityLite
             indentLevel--;
             return result;
         }
-    
-        /**
-         * '%' identifier
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitExternalConstant(FHIRPathParser.ExternalConstantContext ctx) {
             debug(ctx);
@@ -1072,10 +951,7 @@ public Collection<FHIRPathNode> visitExternalConstant(FHIRPathParser.ExternalCon
             indentLevel--;
             return evaluationContext.getExternalConstant(identifier);
         }
-    
-        /**
-         * identifier
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitMemberInvocation(FHIRPathParser.MemberInvocationContext ctx) {
             debug(ctx);
@@ -1101,9 +977,6 @@ public Collection<FHIRPathNode> visitMemberInvocation(FHIRPathParser.MemberInvoc
             return result;
         }
         
-        /**
-         * function
-         */
         @Override
         public Collection<FHIRPathNode> visitFunctionInvocation(FHIRPathParser.FunctionInvocationContext ctx) {
             debug(ctx);
@@ -1112,19 +985,13 @@ public Collection<FHIRPathNode> visitFunctionInvocation(FHIRPathParser.FunctionI
             indentLevel--;
             return result;
         }
-    
-        /**
-         * '$this'
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitThisInvocation(FHIRPathParser.ThisInvocationContext ctx) {
             debug(ctx);
             return getCurrentContext();
         }
-    
-        /**
-         * '$index'
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitIndexInvocation(FHIRPathParser.IndexInvocationContext ctx) {
             debug(ctx);
@@ -1133,10 +1000,7 @@ public Collection<FHIRPathNode> visitIndexInvocation(FHIRPathParser.IndexInvocat
             indentLevel--;
             return result;
         }
-    
-        /**
-         * '$total'
-         */
+        
         @Override
         public Collection<FHIRPathNode> visitTotalInvocation(FHIRPathParser.TotalInvocationContext ctx) {
             debug(ctx);
@@ -1146,9 +1010,6 @@ public Collection<FHIRPathNode> visitTotalInvocation(FHIRPathParser.TotalInvocat
             return result;
         }
         
-        /**
-         * identifier '(' paramList? ')'
-         */
         @Override
         public Collection<FHIRPathNode> visitFunction(FHIRPathParser.FunctionContext ctx) {
             debug(ctx);
@@ -1229,14 +1090,8 @@ public Collection<FHIRPathNode> visitQuantity(FHIRPathParser.QuantityContext ctx
             String number = ctx.NUMBER().getText();
             String text = ctx.unit().getText();
             String unit = text.substring(1, text.length() - 1);
-            
-            Quantity quantity = Quantity.builder()
-                    .value(Decimal.of(number))
-                    .unit(string(unit))
-                    .build();
-            
             indentLevel--;
-            return singleton(FHIRPathQuantityNode.builder(quantity).build());
+            return singleton(FHIRPathQuantityValue.quantityValue(new BigDecimal(number), unit));
         }
     
         @Override
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AllFalseFunction.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AllFalseFunction.java
index 4f344e258ca..68e5426c8fd 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AllFalseFunction.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AllFalseFunction.java
@@ -33,9 +33,9 @@ public int getMaxArity() {
     
     @Override
     public Collection<FHIRPathNode> apply(EvaluationContext evaluationContext, Collection<FHIRPathNode> context, List<Collection<FHIRPathNode>> arguments) {
-        return context.stream().allMatch(node -> node.isPrimitiveValue() && 
-                    node.asPrimitiveValue().isBooleanValue() && 
-                    node.asPrimitiveValue().asBooleanValue().isFalse()) ? 
+        return context.stream().allMatch(node -> node.isSystemValue() && 
+                    node.asSystemValue().isBooleanValue() && 
+                    node.asSystemValue().asBooleanValue().isFalse()) ? 
                             SINGLETON_TRUE : SINGLETON_FALSE;
     }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AllTrueFunction.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AllTrueFunction.java
index 91239c43b97..59f138baa82 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AllTrueFunction.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AllTrueFunction.java
@@ -33,9 +33,9 @@ public int getMaxArity() {
     
     @Override
     public Collection<FHIRPathNode> apply(EvaluationContext evaluationContext, Collection<FHIRPathNode> context, List<Collection<FHIRPathNode>> arguments) {
-        return context.stream().allMatch(node -> node.isPrimitiveValue() && 
-                    node.asPrimitiveValue().isBooleanValue() && 
-                    node.asPrimitiveValue().asBooleanValue().isTrue()) ? 
+        return context.stream().allMatch(node -> node.isSystemValue() && 
+                    node.asSystemValue().isBooleanValue() && 
+                    node.asSystemValue().asBooleanValue().isTrue()) ? 
                             SINGLETON_TRUE : SINGLETON_FALSE;
     }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AnyFalseFunction.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AnyFalseFunction.java
index e0a18de0573..5576daef489 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AnyFalseFunction.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AnyFalseFunction.java
@@ -33,9 +33,9 @@ public int getMaxArity() {
     
     @Override
     public Collection<FHIRPathNode> apply(EvaluationContext evaluationContext, Collection<FHIRPathNode> context, List<Collection<FHIRPathNode>> arguments) {
-        return context.stream().anyMatch(node -> node.isPrimitiveValue() && 
-                    node.asPrimitiveValue().isBooleanValue() && 
-                    node.asPrimitiveValue().asBooleanValue().isFalse()) ? 
+        return context.stream().anyMatch(node -> node.isSystemValue() && 
+                    node.asSystemValue().isBooleanValue() && 
+                    node.asSystemValue().asBooleanValue().isFalse()) ? 
                             SINGLETON_TRUE : SINGLETON_FALSE;
     }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AnyTrueFunction.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AnyTrueFunction.java
index 01c71f9680b..137e856a3f0 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AnyTrueFunction.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/AnyTrueFunction.java
@@ -33,9 +33,9 @@ public int getMaxArity() {
     
     @Override
     public Collection<FHIRPathNode> apply(EvaluationContext evaluationContext, Collection<FHIRPathNode> context, List<Collection<FHIRPathNode>> arguments) {
-        return context.stream().anyMatch(node -> node.isPrimitiveValue() && 
-                    node.asPrimitiveValue().isBooleanValue() && 
-                    node.asPrimitiveValue().asBooleanValue().isTrue()) ? 
+        return context.stream().anyMatch(node -> node.isSystemValue() && 
+                    node.asSystemValue().isBooleanValue() && 
+                    node.asSystemValue().asBooleanValue().isTrue()) ? 
                             SINGLETON_TRUE : SINGLETON_FALSE;
     }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ConformsToFunction.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ConformsToFunction.java
index 01098bbed2a..47295b92566 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ConformsToFunction.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ConformsToFunction.java
@@ -6,6 +6,14 @@
 
 package com.ibm.fhir.model.path.function;
 
+import static com.ibm.fhir.model.path.evaluator.FHIRPathEvaluator.SINGLETON_TRUE;
+
+import java.util.Collection;
+import java.util.List;
+
+import com.ibm.fhir.model.path.FHIRPathNode;
+import com.ibm.fhir.model.path.evaluator.FHIRPathEvaluator.EvaluationContext;
+
 public class ConformsToFunction extends FHIRPathAbstractFunction {
     @Override
     public String getName() {
@@ -21,4 +29,9 @@ public int getMinArity() {
     public int getMaxArity() {
         return 1;
     }
+    
+    @Override
+    public Collection<FHIRPathNode> apply(EvaluationContext evaluationContext, Collection<FHIRPathNode> context, List<Collection<FHIRPathNode>> arguments) {
+        return SINGLETON_TRUE;
+    }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ExtensionFunction.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ExtensionFunction.java
index 630723fedeb..b8eaabc026b 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ExtensionFunction.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ExtensionFunction.java
@@ -6,6 +6,17 @@
 
 package com.ibm.fhir.model.path.function;
 
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.getStringValue;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.hasStringValue;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+import com.ibm.fhir.model.path.FHIRPathNode;
+import com.ibm.fhir.model.path.evaluator.FHIRPathEvaluator.EvaluationContext;
+import com.ibm.fhir.model.type.Extension;
+
 public class ExtensionFunction extends FHIRPathAbstractFunction {
     @Override
     public String getName() {
@@ -21,4 +32,21 @@ public int getMinArity() {
     public int getMaxArity() {
         return 1;
     }
+    
+    @Override
+    public Collection<FHIRPathNode> apply(EvaluationContext evaluationContext, Collection<FHIRPathNode> context, List<Collection<FHIRPathNode>> arguments) {
+        List<FHIRPathNode> result = new ArrayList<>();
+        if (hasStringValue(arguments.get(0))) {
+            String url = getStringValue(arguments.get(0)).string();
+            for (FHIRPathNode node : context) {
+                if (node.isElementNode() && node.asElementNode().element().is(Extension.class)) {
+                    Extension extension = node.asElementNode().element().as(Extension.class);
+                    if (extension.getUrl().equals(url)) {
+                        result.add(node);
+                    }
+                } 
+            }      
+        }
+        return result;
+    }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/MemberOfFunction.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/MemberOfFunction.java
index 9dae1c3a6b3..39ba9f6b14f 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/MemberOfFunction.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/MemberOfFunction.java
@@ -6,6 +6,14 @@
 
 package com.ibm.fhir.model.path.function;
 
+import static com.ibm.fhir.model.path.evaluator.FHIRPathEvaluator.SINGLETON_TRUE;
+
+import java.util.Collection;
+import java.util.List;
+
+import com.ibm.fhir.model.path.FHIRPathNode;
+import com.ibm.fhir.model.path.evaluator.FHIRPathEvaluator.EvaluationContext;
+
 public class MemberOfFunction extends FHIRPathAbstractFunction {
     @Override
     public String getName() {
@@ -21,4 +29,9 @@ public int getMinArity() {
     public int getMaxArity() {
         return 1;
     }
+    
+    @Override
+    public Collection<FHIRPathNode> apply(EvaluationContext evaluationContext, Collection<FHIRPathNode> context, List<Collection<FHIRPathNode>> arguments) {
+        return SINGLETON_TRUE;
+    }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ToIntegerFunction.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ToIntegerFunction.java
index d9ff617cd36..5e19f856c31 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ToIntegerFunction.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ToIntegerFunction.java
@@ -8,15 +8,15 @@
 
 import static com.ibm.fhir.model.path.FHIRPathIntegerValue.integerValue;
 import static com.ibm.fhir.model.path.util.FHIRPathUtil.empty;
-import static com.ibm.fhir.model.path.util.FHIRPathUtil.getPrimitiveValue;
-import static com.ibm.fhir.model.path.util.FHIRPathUtil.hasPrimitiveValue;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.getSystemValue;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.hasSystemValue;
 import static com.ibm.fhir.model.path.util.FHIRPathUtil.singleton;
 
 import java.util.Collection;
 import java.util.List;
 
 import com.ibm.fhir.model.path.FHIRPathNode;
-import com.ibm.fhir.model.path.FHIRPathPrimitiveValue;
+import com.ibm.fhir.model.path.FHIRPathSystemValue;
 import com.ibm.fhir.model.path.evaluator.FHIRPathEvaluator.EvaluationContext;
 
 public class ToIntegerFunction extends FHIRPathAbstractFunction {
@@ -37,10 +37,10 @@ public int getMaxArity() {
 
     @Override
     public Collection<FHIRPathNode> apply(EvaluationContext evaluationContext, Collection<FHIRPathNode> context, List<Collection<FHIRPathNode>> arguments) {
-        if (!hasPrimitiveValue(context)) {
+        if (!hasSystemValue(context)) {
             return empty();
         }
-        FHIRPathPrimitiveValue value = getPrimitiveValue(context);
+        FHIRPathSystemValue value = getSystemValue(context);
         if (value.isNumberValue() && value.asNumberValue().isIntegerValue()) {
             return singleton(value);
         }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ToStringFunction.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ToStringFunction.java
index 4c0cd95dec7..732b47d2cfd 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ToStringFunction.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/function/ToStringFunction.java
@@ -8,9 +8,8 @@
 
 import static com.ibm.fhir.model.path.FHIRPathStringValue.stringValue;
 import static com.ibm.fhir.model.path.util.FHIRPathUtil.empty;
-import static com.ibm.fhir.model.path.util.FHIRPathUtil.getPrimitiveValue;
-import static com.ibm.fhir.model.path.util.FHIRPathUtil.getSingleton;
-import static com.ibm.fhir.model.path.util.FHIRPathUtil.hasPrimitiveValue;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.getSystemValue;
+import static com.ibm.fhir.model.path.util.FHIRPathUtil.hasSystemValue;
 import static com.ibm.fhir.model.path.util.FHIRPathUtil.isSingleton;
 import static com.ibm.fhir.model.path.util.FHIRPathUtil.singleton;
 
@@ -18,8 +17,7 @@
 import java.util.List;
 
 import com.ibm.fhir.model.path.FHIRPathNode;
-import com.ibm.fhir.model.path.FHIRPathPrimitiveValue;
-import com.ibm.fhir.model.path.FHIRPathQuantityNode;
+import com.ibm.fhir.model.path.FHIRPathSystemValue;
 import com.ibm.fhir.model.path.evaluator.FHIRPathEvaluator.EvaluationContext;
 
 public class ToStringFunction extends FHIRPathAbstractFunction {
@@ -43,14 +41,10 @@ public Collection<FHIRPathNode> apply(EvaluationContext evaluationContext, Colle
         if (!isSingleton(context)) {
             return empty();
         }
-        if (hasPrimitiveValue(context)) {
-            FHIRPathPrimitiveValue value = getPrimitiveValue(context);
+        if (hasSystemValue(context)) {
+            FHIRPathSystemValue value = getSystemValue(context);
             return singleton(stringValue(value.toString()));
         }
-        FHIRPathNode node = getSingleton(context);
-        if (node instanceof FHIRPathQuantityNode) {
-            return singleton(stringValue(node.toString()));
-        }
         return empty();
     }
 }
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/util/FHIRPathUtil.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/util/FHIRPathUtil.java
index cec5b9d76a0..fbdbf586330 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/util/FHIRPathUtil.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/util/FHIRPathUtil.java
@@ -34,9 +34,11 @@
 import com.ibm.fhir.model.path.FHIRPathIntegerValue;
 import com.ibm.fhir.model.path.FHIRPathNode;
 import com.ibm.fhir.model.path.FHIRPathNumberValue;
-import com.ibm.fhir.model.path.FHIRPathPrimitiveValue;
 import com.ibm.fhir.model.path.FHIRPathQuantityNode;
+import com.ibm.fhir.model.path.FHIRPathQuantityValue;
 import com.ibm.fhir.model.path.FHIRPathStringValue;
+import com.ibm.fhir.model.path.FHIRPathSystemValue;
+import com.ibm.fhir.model.path.FHIRPathTemporalValue;
 import com.ibm.fhir.model.path.FHIRPathType;
 import com.ibm.fhir.model.path.SimpleTypeInfo;
 import com.ibm.fhir.model.path.TupleTypeInfo;
@@ -89,75 +91,107 @@ public static String delimit(String identifier) {
         return String.format("`%s`", identifier);
     }
     
+    public static boolean hasQuantityNode(Collection<FHIRPathNode> nodes) {
+        if (isSingleton(nodes)) {
+            FHIRPathNode node = getSingleton(nodes);
+            return (node instanceof FHIRPathQuantityNode);
+        }
+        return false;
+    }
+    
+    public static FHIRPathQuantityNode getQuantityNode(Collection<FHIRPathNode> nodes) {
+        return getSingleton(nodes).asElementNode().asQuantityNode();
+    }
+    
     public static BigDecimal getDecimal(Collection<FHIRPathNode> nodes) {
-        return getPrimitiveValue(nodes).asNumberValue().decimal();
+        return getSystemValue(nodes).asNumberValue().decimal();
     }
     
     public static Integer getInteger(Collection<FHIRPathNode> nodes) {
-        return getPrimitiveValue(nodes).asNumberValue().asIntegerValue().integer();
+        return getSystemValue(nodes).asNumberValue().asIntegerValue().integer();
     }
     
     public static String getString(Collection<FHIRPathNode> nodes) {
-        return getPrimitiveValue(nodes).asStringValue().string();
+        return getSystemValue(nodes).asStringValue().string();
     }
     
     public static Boolean getBoolean(Collection<FHIRPathNode> nodes) {
-        return getPrimitiveValue(nodes).asBooleanValue()._boolean();
+        return getSystemValue(nodes).asBooleanValue()._boolean();
+    }
+    
+    public static TemporalAccessor getDate(Collection<FHIRPathNode> nodes) {
+        return getSystemValue(nodes).asTemporalValue().asDateValue().date();
     }
     
     public static TemporalAccessor getDateTime(Collection<FHIRPathNode> nodes) {
-        return getPrimitiveValue(nodes).asDateTimeValue().dateTime();
+        return getSystemValue(nodes).asTemporalValue().asDateTimeValue().dateTime();
     }
     
     public static TemporalAccessor getTime(Collection<FHIRPathNode> nodes) {
-        return getPrimitiveValue(nodes).asTimeValue().time();
+        return getSystemValue(nodes).asTemporalValue().asTimeValue().time();
     }
     
-    public static boolean hasPrimitiveValue(Collection<FHIRPathNode> nodes) {
+    public static boolean hasSystemValue(Collection<FHIRPathNode> nodes) {
         if (isSingleton(nodes)) {
             FHIRPathNode node = getSingleton(nodes);
-            return (node instanceof FHIRPathPrimitiveValue) || node.hasValue();
+            return (node instanceof FHIRPathSystemValue) || node.hasValue();
         }
         return false;
     }
     
-    public static FHIRPathPrimitiveValue getPrimitiveValue(Collection<FHIRPathNode> nodes) {
-        if (!hasPrimitiveValue(nodes)) {
+    public static FHIRPathSystemValue getSystemValue(Collection<FHIRPathNode> nodes) {
+        if (!hasSystemValue(nodes)) {
             throw new IllegalArgumentException();
         }
         FHIRPathNode node = getSingleton(nodes);
-        if (node instanceof FHIRPathPrimitiveValue) {
-            return (FHIRPathPrimitiveValue) node;
+        if (node instanceof FHIRPathSystemValue) {
+            return (FHIRPathSystemValue) node;
         }
         return node.getValue();
     }
     
     public static FHIRPathStringValue getStringValue(Collection<FHIRPathNode> nodes) {
-        return getPrimitiveValue(nodes).asStringValue();
+        return getSystemValue(nodes).asStringValue();
+    }
+    
+    public static FHIRPathQuantityValue getQuantityValue(Collection<FHIRPathNode> nodes) {
+        return getSystemValue(nodes).asQuantityValue();
     }
     
     public static FHIRPathIntegerValue getIntegerValue(Collection<FHIRPathNode> nodes) {
-        return getPrimitiveValue(nodes).asNumberValue().asIntegerValue();
+        return getSystemValue(nodes).asNumberValue().asIntegerValue();
     }
     
     public static FHIRPathNumberValue getNumberValue(Collection<FHIRPathNode> nodes) {
-        return getPrimitiveValue(nodes).asNumberValue();
+        return getSystemValue(nodes).asNumberValue();
+    }
+    
+    public static FHIRPathTemporalValue getTemporalValue(Collection<FHIRPathNode> nodes) {
+        return getSystemValue(nodes).asTemporalValue();
     }
     
     public static FHIRPathBooleanValue getBooleanValue(Collection<FHIRPathNode> nodes) {
-        return getPrimitiveValue(nodes).asBooleanValue();
+        return getSystemValue(nodes).asBooleanValue();
     }
     
     public static boolean hasBooleanValue(Collection<FHIRPathNode> nodes) {
-        return hasPrimitiveValue(nodes) && getPrimitiveValue(nodes).isBooleanValue();
+        return hasSystemValue(nodes) && getSystemValue(nodes).isBooleanValue();
     }
     
     public static boolean hasNumberValue(Collection<FHIRPathNode> nodes) {
-        return hasPrimitiveValue(nodes) && getPrimitiveValue(nodes).isNumberValue();
+        return hasSystemValue(nodes) && getSystemValue(nodes).isNumberValue();
+    }
+    
+    public static boolean hasTemporalValue(Collection<FHIRPathNode> nodes) {
+        return hasSystemValue(nodes) && getSystemValue(nodes).isTemporalValue();
     }
     
     public static boolean hasStringValue(Collection<FHIRPathNode> nodes) {
-        return hasPrimitiveValue(nodes) && getPrimitiveValue(nodes).isStringValue();
+        return hasSystemValue(nodes) && getSystemValue(nodes).isStringValue();
+    }
+    
+    public static boolean hasQuantityValue(Collection<FHIRPathNode> nodes) {
+        return hasSystemValue(nodes) && getSystemValue(nodes).isQuantityValue();
     }
     
     public static boolean evaluatesToBoolean(Collection<FHIRPathNode> nodes) {
@@ -198,10 +232,6 @@ public static Collection<FHIRPathNode> empty() {
         return emptyList();
     }
     
-    public static boolean hasValueAndUnit(FHIRPathQuantityNode quantityNode) {
-        return quantityNode.getQuantityValue() != null && quantityNode.getQuantityUnit() != null;
-    }
-    
     public static TemporalAccessor getTemporalAccessor(Temporal temporal, Class<?> targetType) {
         if (temporal.getClass().equals(targetType)) {
             return temporal;
@@ -237,12 +267,9 @@ public static Temporal getTemporal(TemporalAccessor temporalAccessor) {
         throw new IllegalArgumentException();
     }
 
-    public static TemporalAmount getTemporalAmount(FHIRPathQuantityNode quantityNode) {
-        if (!hasValueAndUnit(quantityNode)) {
-            throw new IllegalArgumentException();
-        }
-        int value = quantityNode.getQuantityValue().intValue();
-        String unit = quantityNode.getQuantityUnit();        
+    public static TemporalAmount getTemporalAmount(FHIRPathQuantityValue quantityValue) {
+        int value = quantityValue.value().intValue();
+        String unit = quantityValue.unit();        
         switch (unit) {
         case "year":
         case "years":
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathAbstractNodeVisitor.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathAbstractNodeVisitor.java
deleted file mode 100644
index 8b5328ec47c..00000000000
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathAbstractNodeVisitor.java
+++ /dev/null
@@ -1,92 +0,0 @@
-/*
- * (C) Copyright IBM Corp. 2019
- * 
- * SPDX-License-Identifier: Apache-2.0
- */
-
-package com.ibm.fhir.model.path.visitor;
-
-import com.ibm.fhir.model.path.FHIRPathBooleanValue;
-import com.ibm.fhir.model.path.FHIRPathDateTimeValue;
-import com.ibm.fhir.model.path.FHIRPathDecimalValue;
-import com.ibm.fhir.model.path.FHIRPathElementNode;
-import com.ibm.fhir.model.path.FHIRPathIntegerValue;
-import com.ibm.fhir.model.path.FHIRPathNode;
-import com.ibm.fhir.model.path.FHIRPathQuantityNode;
-import com.ibm.fhir.model.path.FHIRPathResourceNode;
-import com.ibm.fhir.model.path.FHIRPathStringValue;
-import com.ibm.fhir.model.path.FHIRPathTimeValue;
-import com.ibm.fhir.model.path.FHIRPathTypeInfoNode;
-
-public abstract class FHIRPathAbstractNodeVisitor<T> implements FHIRPathNodeVisitor<T> {
-    // called by template methods
-    protected abstract void doVisit(T param, FHIRPathBooleanValue value);
-    protected abstract void doVisit(T param, FHIRPathDateTimeValue value);
-    protected abstract void doVisit(T param, FHIRPathDecimalValue value);
-    protected abstract void doVisit(T param, FHIRPathElementNode node);
-    protected abstract void doVisit(T param, FHIRPathIntegerValue value);
-    protected abstract void doVisit(T param, FHIRPathQuantityNode node);
-    protected abstract void doVisit(T param, FHIRPathResourceNode node);
-    protected abstract void doVisit(T param, FHIRPathStringValue value);
-    protected abstract void doVisit(T param, FHIRPathTimeValue value);
-    protected abstract void doVisit(T param, FHIRPathTypeInfoNode node);
-    
-    @Override
-    public final void visit(T param, FHIRPathBooleanValue value) {
-        doVisit(param, value);
-    }
-
-    @Override
-    public final void visit(T param, FHIRPathDateTimeValue value) {
-        doVisit(param, value);
-    }
-    
-    @Override
-    public final void visit(T param, FHIRPathDecimalValue value) {
-        doVisit(param, value);
-    }
-
-    @Override
-    public final void visit(T param, FHIRPathElementNode node) {
-        doVisit(param, node);
-        visitChildren(param, node);
-    }
-
-    @Override
-    public final void visit(T param, FHIRPathIntegerValue value) {
-        doVisit(param, value);
-    }
-
-    @Override
-    public final void visit(T param, FHIRPathQuantityNode node) {
-        doVisit(param, node);
-        visitChildren(param, node);
-    }
-
-    @Override
-    public final void visit(T param, FHIRPathResourceNode node) {
-        doVisit(param, node);
-        visitChildren(param, node);
-    }
-
-    @Override
-    public final void visit(T param, FHIRPathStringValue value) {
-        doVisit(param, value);
-    }
-
-    @Override
-    public final void visit(T param, FHIRPathTimeValue value) {
-        doVisit(param, value);
-    }
-    
-    @Override
-    public final void visit(T param, FHIRPathTypeInfoNode node) {
-        doVisit(param, node);
-    }
-
-    private void visitChildren(T param, FHIRPathNode node) {
-        for (FHIRPathNode child : node.children()) {
-            child.accept(param, this);
-        }
-    }
-}
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathDefaultNodeVisitor.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathDefaultNodeVisitor.java
new file mode 100644
index 00000000000..8b7d1b8307b
--- /dev/null
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathDefaultNodeVisitor.java
@@ -0,0 +1,99 @@
+/*
+ * (C) Copyright IBM Corp. 2019
+ * 
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.ibm.fhir.model.path.visitor;
+
+import com.ibm.fhir.model.path.FHIRPathBooleanValue;
+import com.ibm.fhir.model.path.FHIRPathDateTimeValue;
+import com.ibm.fhir.model.path.FHIRPathDateValue;
+import com.ibm.fhir.model.path.FHIRPathDecimalValue;
+import com.ibm.fhir.model.path.FHIRPathElementNode;
+import com.ibm.fhir.model.path.FHIRPathIntegerValue;
+import com.ibm.fhir.model.path.FHIRPathNode;
+import com.ibm.fhir.model.path.FHIRPathQuantityNode;
+import com.ibm.fhir.model.path.FHIRPathQuantityValue;
+import com.ibm.fhir.model.path.FHIRPathResourceNode;
+import com.ibm.fhir.model.path.FHIRPathStringValue;
+import com.ibm.fhir.model.path.FHIRPathTimeValue;
+import com.ibm.fhir.model.path.FHIRPathTypeInfoNode;
+
+public class FHIRPathDefaultNodeVisitor implements FHIRPathNodeVisitor {
+    protected void doVisit(FHIRPathResourceNode node) {
+        // do nothing
+    }
+    
+    protected void doVisit(FHIRPathElementNode node) {
+        // do nothing
+    }
+    
+    protected void visitChildren(FHIRPathNode node) {
+        for (FHIRPathNode child : node.children()) {
+            child.accept(this);
+        }
+    }
+    
+    @Override
+    public void visit(FHIRPathBooleanValue value) {
+        // do nothing
+    }
+
+    @Override
+    public void visit(FHIRPathDateValue value) {
+        // do nothing
+    }
+
+    @Override
+    public void visit(FHIRPathDateTimeValue value) {
+        // do nothing
+    }
+
+    @Override
+    public void visit(FHIRPathDecimalValue value) {
+        // do nothing
+    }
+
+    @Override
+    public final void visit(FHIRPathElementNode node) {
+        doVisit(node);
+        visitChildren(node);
+    }
+
+    @Override
+    public void visit(FHIRPathIntegerValue value) {
+        // do nothing
+    }
+
+    @Override
+    public void visit(FHIRPathQuantityValue value) {
+        // do nothing
+    }
+    
+    @Override
+    public void visit(FHIRPathQuantityNode node) {
+        visit((FHIRPathElementNode) node);
+    }
+
+    @Override
+    public final void visit(FHIRPathResourceNode node) {
+        doVisit(node);
+        visitChildren(node);
+    }
+
+    @Override
+    public void visit(FHIRPathStringValue value) {
+        // do nothing
+    }
+
+    @Override
+    public void visit(FHIRPathTimeValue value) {
+        // do nothing
+    }
+
+    @Override
+    public void visit(FHIRPathTypeInfoNode node) {
+        // do nothing
+    }
+}
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathNodeVisitor.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathNodeVisitor.java
index 57a31fbcf25..f8fe770b69f 100644
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathNodeVisitor.java
+++ b/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathNodeVisitor.java
@@ -8,24 +8,28 @@
 
 import com.ibm.fhir.model.path.FHIRPathBooleanValue;
 import com.ibm.fhir.model.path.FHIRPathDateTimeValue;
+import com.ibm.fhir.model.path.FHIRPathDateValue;
 import com.ibm.fhir.model.path.FHIRPathDecimalValue;
 import com.ibm.fhir.model.path.FHIRPathElementNode;
 import com.ibm.fhir.model.path.FHIRPathIntegerValue;
 import com.ibm.fhir.model.path.FHIRPathQuantityNode;
+import com.ibm.fhir.model.path.FHIRPathQuantityValue;
 import com.ibm.fhir.model.path.FHIRPathResourceNode;
 import com.ibm.fhir.model.path.FHIRPathStringValue;
 import com.ibm.fhir.model.path.FHIRPathTimeValue;
 import com.ibm.fhir.model.path.FHIRPathTypeInfoNode;
 
-public interface FHIRPathNodeVisitor<T> {
-    void visit(T param, FHIRPathBooleanValue value);
-    void visit(T param, FHIRPathDateTimeValue value);
-    void visit(T param, FHIRPathDecimalValue value);
-    void visit(T param, FHIRPathElementNode node);
-    void visit(T param, FHIRPathIntegerValue value);
-    void visit(T param, FHIRPathQuantityNode node);
-    void visit(T param, FHIRPathResourceNode node);
-    void visit(T param, FHIRPathStringValue value);
-    void visit(T param, FHIRPathTimeValue value);
-    void visit(T param, FHIRPathTypeInfoNode node);
+public interface FHIRPathNodeVisitor {
+    void visit(FHIRPathBooleanValue value);
+    void visit(FHIRPathDateValue value);
+    void visit(FHIRPathDateTimeValue value);
+    void visit(FHIRPathDecimalValue value);
+    void visit(FHIRPathElementNode node);
+    void visit(FHIRPathIntegerValue value);
+    void visit(FHIRPathQuantityNode node);
+    void visit(FHIRPathQuantityValue value);
+    void visit(FHIRPathResourceNode node);
+    void visit(FHIRPathStringValue value);
+    void visit(FHIRPathTimeValue value);
+    void visit(FHIRPathTypeInfoNode node);
 }
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathNodeVisitorAdapter.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathNodeVisitorAdapter.java
deleted file mode 100644
index 5b8db65ff39..00000000000
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathNodeVisitorAdapter.java
+++ /dev/null
@@ -1,70 +0,0 @@
-/*
- * (C) Copyright IBM Corp. 2019
- * 
- * SPDX-License-Identifier: Apache-2.0
- */
-
-package com.ibm.fhir.model.path.visitor;
-
-import com.ibm.fhir.model.path.FHIRPathBooleanValue;
-import com.ibm.fhir.model.path.FHIRPathDateTimeValue;
-import com.ibm.fhir.model.path.FHIRPathDecimalValue;
-import com.ibm.fhir.model.path.FHIRPathElementNode;
-import com.ibm.fhir.model.path.FHIRPathIntegerValue;
-import com.ibm.fhir.model.path.FHIRPathQuantityNode;
-import com.ibm.fhir.model.path.FHIRPathResourceNode;
-import com.ibm.fhir.model.path.FHIRPathStringValue;
-import com.ibm.fhir.model.path.FHIRPathTimeValue;
-import com.ibm.fhir.model.path.FHIRPathTypeInfoNode;
-
-public class FHIRPathNodeVisitorAdapter<T> extends FHIRPathAbstractNodeVisitor<T> {
-    @Override
-    protected void doVisit(T param, FHIRPathBooleanValue value) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(T param, FHIRPathDateTimeValue value) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(T param, FHIRPathDecimalValue value) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(T param, FHIRPathElementNode node) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(T param, FHIRPathIntegerValue value) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(T param, FHIRPathQuantityNode node) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(T param, FHIRPathResourceNode node) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(T param, FHIRPathStringValue value) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(T param, FHIRPathTimeValue value) {
-        // do nothing
-    }
-    
-    @Override
-    protected void doVisit(T param, FHIRPathTypeInfoNode node) {
-        // do nothing
-    }
-}
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathVoidParameterAbstractNodeVisitor.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathVoidParameterAbstractNodeVisitor.java
deleted file mode 100644
index fbea5ee7605..00000000000
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathVoidParameterAbstractNodeVisitor.java
+++ /dev/null
@@ -1,80 +0,0 @@
-/*
- * (C) Copyright IBM Corp. 2019
- * SPDX-License-Identifier: Apache-2.0
- */
-package com.ibm.fhir.model.path.visitor;
-
-import com.ibm.fhir.model.path.FHIRPathBooleanValue;
-import com.ibm.fhir.model.path.FHIRPathDateTimeValue;
-import com.ibm.fhir.model.path.FHIRPathDecimalValue;
-import com.ibm.fhir.model.path.FHIRPathElementNode;
-import com.ibm.fhir.model.path.FHIRPathIntegerValue;
-import com.ibm.fhir.model.path.FHIRPathQuantityNode;
-import com.ibm.fhir.model.path.FHIRPathResourceNode;
-import com.ibm.fhir.model.path.FHIRPathStringValue;
-import com.ibm.fhir.model.path.FHIRPathTimeValue;
-import com.ibm.fhir.model.path.FHIRPathTypeInfoNode;
-
-public abstract class FHIRPathVoidParameterAbstractNodeVisitor extends FHIRPathAbstractNodeVisitor<Void> {
-    // called by template methods
-    protected abstract void doVisit(FHIRPathBooleanValue value);
-    protected abstract void doVisit(FHIRPathDateTimeValue value);
-    protected abstract void doVisit(FHIRPathDecimalValue value);
-    protected abstract void doVisit(FHIRPathElementNode node);
-    protected abstract void doVisit(FHIRPathIntegerValue value);
-    protected abstract void doVisit(FHIRPathQuantityNode node);
-    protected abstract void doVisit(FHIRPathResourceNode node);
-    protected abstract void doVisit(FHIRPathStringValue value);
-    protected abstract void doVisit(FHIRPathTimeValue value);
-    protected abstract void doVisit(FHIRPathTypeInfoNode node);
-
-    @Override
-    protected final void doVisit(Void param, FHIRPathBooleanValue value) {
-        doVisit(value);
-    }
-
-    @Override
-    protected final void doVisit(Void param, FHIRPathDateTimeValue value) {
-        doVisit(value);
-    }
-
-    @Override
-    protected final void doVisit(Void param, FHIRPathDecimalValue value) {
-        doVisit(value);
-    }
-
-    @Override
-    protected final void doVisit(Void param, FHIRPathElementNode node) {
-        doVisit(node);
-    }
-
-    @Override
-    protected final void doVisit(Void param, FHIRPathIntegerValue value) {
-        doVisit(value);
-    }
-
-    @Override
-    protected final void doVisit(Void param, FHIRPathQuantityNode node) {
-        doVisit(node);
-    }
-
-    @Override
-    protected final void doVisit(Void param, FHIRPathResourceNode node) {
-        doVisit(node);
-    }
-
-    @Override
-    protected final void doVisit(Void param, FHIRPathStringValue value) {
-        doVisit(value);
-    }
-
-    @Override
-    protected final void doVisit(Void param, FHIRPathTimeValue value) {
-        doVisit(value);
-    }
-    
-    @Override
-    protected final void doVisit(Void param, FHIRPathTypeInfoNode node) {
-        doVisit(node);
-    }
-}
\ No newline at end of file
diff --git a/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathVoidParameterNodeVisitorAdapter.java b/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathVoidParameterNodeVisitorAdapter.java
deleted file mode 100644
index 448c8614bc2..00000000000
--- a/fhir-model/src/main/java/com/ibm/fhir/model/path/visitor/FHIRPathVoidParameterNodeVisitorAdapter.java
+++ /dev/null
@@ -1,68 +0,0 @@
-/*
- * (C) Copyright IBM Corp. 2019
- * SPDX-License-Identifier: Apache-2.0
- */
-package com.ibm.fhir.model.path.visitor;
-
-import com.ibm.fhir.model.path.FHIRPathBooleanValue;
-import com.ibm.fhir.model.path.FHIRPathDateTimeValue;
-import com.ibm.fhir.model.path.FHIRPathDecimalValue;
-import com.ibm.fhir.model.path.FHIRPathElementNode;
-import com.ibm.fhir.model.path.FHIRPathIntegerValue;
-import com.ibm.fhir.model.path.FHIRPathQuantityNode;
-import com.ibm.fhir.model.path.FHIRPathResourceNode;
-import com.ibm.fhir.model.path.FHIRPathStringValue;
-import com.ibm.fhir.model.path.FHIRPathTimeValue;
-import com.ibm.fhir.model.path.FHIRPathTypeInfoNode;
-
-public class FHIRPathVoidParameterNodeVisitorAdapter extends FHIRPathVoidParameterAbstractNodeVisitor {
-    @Override
-    protected void doVisit(FHIRPathBooleanValue value) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(FHIRPathDateTimeValue value) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(FHIRPathDecimalValue value) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(FHIRPathElementNode node) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(FHIRPathIntegerValue value) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(FHIRPathQuantityNode node) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(FHIRPathResourceNode node) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(FHIRPathStringValue value) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(FHIRPathTimeValue value) {
-        // do nothing
-    }
-
-    @Override
-    protected void doVisit(FHIRPathTypeInfoNode node) {
-        // do nothing
-    }
-}
\ No newline at end of file
diff --git a/fhir-model/src/test/java/com/ibm/fhir/model/path/test/FHIRPathNodeVisitorTest.java b/fhir-model/src/test/java/com/ibm/fhir/model/path/test/FHIRPathNodeVisitorTest.java
index 460caf56f02..1e9c381cb7d 100644
--- a/fhir-model/src/test/java/com/ibm/fhir/model/path/test/FHIRPathNodeVisitorTest.java
+++ b/fhir-model/src/test/java/com/ibm/fhir/model/path/test/FHIRPathNodeVisitorTest.java
@@ -22,13 +22,13 @@
 import com.ibm.fhir.model.path.FHIRPathDecimalValue;
 import com.ibm.fhir.model.path.FHIRPathElementNode;
 import com.ibm.fhir.model.path.FHIRPathIntegerValue;
-import com.ibm.fhir.model.path.FHIRPathQuantityNode;
+import com.ibm.fhir.model.path.FHIRPathQuantityValue;
 import com.ibm.fhir.model.path.FHIRPathResourceNode;
 import com.ibm.fhir.model.path.FHIRPathStringValue;
 import com.ibm.fhir.model.path.FHIRPathTimeValue;
 import com.ibm.fhir.model.path.FHIRPathTree;
 import com.ibm.fhir.model.path.FHIRPathTypeInfoNode;
-import com.ibm.fhir.model.path.visitor.FHIRPathAbstractNodeVisitor;
+import com.ibm.fhir.model.path.visitor.FHIRPathDefaultNodeVisitor;
 import com.ibm.fhir.model.resource.Patient;
 import com.ibm.fhir.model.type.Boolean;
 import com.ibm.fhir.model.type.Date;
@@ -48,7 +48,7 @@ public class FHIRPathNodeVisitorTest {
         "FHIRPathElementNode: Id", 
         "FHIRPathStringValue: 1", 
         "FHIRPathElementNode: Instant", 
-        "FHIRPathBooleanValue: 2019-08-20T20:09:30.841Z", 
+        "FHIRPathDateTimeValue: 2019-08-20T20:09:30.841Z", 
         "FHIRPathElementNode: Narrative", 
         "FHIRPathElementNode: NarrativeStatus", 
         "FHIRPathStringValue: generated", 
@@ -62,7 +62,7 @@ public class FHIRPathNodeVisitorTest {
         "FHIRPathElementNode: String", 
         "FHIRPathStringValue: John", 
         "FHIRPathElementNode: Date", 
-        "FHIRPathBooleanValue: 1980-01-01"
+        "FHIRPathDateTimeValue: 1980-01-01"
     );
     
     @BeforeClass
@@ -72,61 +72,67 @@ public void setUp() {
     @Test
     public void testFHIRPathNodeVisitor() {
         Patient patient = buildPatient();
-        FHIRPathTree tree = FHIRPathTree.tree(patient);
-        List<String> list = new ArrayList<>();
-        tree.getRoot().accept(list, new ListBuildingVisitor());
-        Assert.assertEquals(list, EXPECTED);
+        FHIRPathTree tree = FHIRPathTree.tree(patient);        
+        ListBuildingVisitor visitor = new ListBuildingVisitor();
+        tree.getRoot().accept(visitor);
+        Assert.assertEquals(visitor.getResult(), EXPECTED);
     }
     
-    public static class ListBuildingVisitor extends FHIRPathAbstractNodeVisitor<List<String>> {
+    public static class ListBuildingVisitor extends FHIRPathDefaultNodeVisitor {
+        private List<String> result = new ArrayList<>();
+        
+        public List<String> getResult() {
+            return result;
+        }
+        
         @Override
-        protected void doVisit(List<String> param, FHIRPathBooleanValue value) {
-            param.add("FHIRPathBooleanValue: " + value._boolean());
+        public void visit(FHIRPathBooleanValue value) {
+            result.add("FHIRPathBooleanValue: " + value._boolean());
         }
 
         @Override
-        protected void doVisit(List<String> param, FHIRPathDateTimeValue value) {
-            param.add("FHIRPathBooleanValue: " + value.dateTime());
+        public void visit(FHIRPathDateTimeValue value) {
+            result.add("FHIRPathDateTimeValue: " + value.dateTime());
         }
 
         @Override
-        protected void doVisit(List<String> param, FHIRPathDecimalValue value) {
-            param.add("FHIRPathDecimalValue: " + value.decimal());
+        public void visit(FHIRPathDecimalValue value) {
+            result.add("FHIRPathDecimalValue: " + value.decimal());
         }
 
         @Override
-        protected void doVisit(List<String> param, FHIRPathElementNode node) {
-            param.add("FHIRPathElementNode: " + node.element().getClass().getSimpleName());
+        public void doVisit(FHIRPathElementNode node) {
+            result.add("FHIRPathElementNode: " + node.element().getClass().getSimpleName());
         }
 
         @Override
-        protected void doVisit(List<String> param, FHIRPathIntegerValue value) {
-            param.add("FHIRPathIntegerValue: " + value.integer());
+        public void visit(FHIRPathIntegerValue value) {
+            result.add("FHIRPathIntegerValue: " + value.integer());
         }
 
         @Override
-        protected void doVisit(List<String> param, FHIRPathQuantityNode node) {
-            param.add("FHIRPathQuantityNode: " + node.quantity());
+        public void visit(FHIRPathQuantityValue value) {
+            result.add("FHIRPathQuantityValue: " + value.toString());
         }
 
         @Override
-        protected void doVisit(List<String> param, FHIRPathResourceNode node) {
-            param.add("FHIRPathResourceNode: " + node.resource().getClass().getSimpleName());
+        public void doVisit(FHIRPathResourceNode node) {
+            result.add("FHIRPathResourceNode: " + node.resource().getClass().getSimpleName());
         }
 
         @Override
-        protected void doVisit(List<String> param, FHIRPathStringValue value) {
-            param.add("FHIRPathStringValue: " + value.string());
+        public void visit(FHIRPathStringValue value) {
+            result.add("FHIRPathStringValue: " + value.string());
         }
 
         @Override
-        protected void doVisit(List<String> param, FHIRPathTimeValue value) {
-            param.add("FHIRPathTimeValue: " + value.time());
+        public void visit(FHIRPathTimeValue value) {
+            result.add("FHIRPathTimeValue: " + value.time());
         }
 
         @Override
-        protected void doVisit(List<String> param, FHIRPathTypeInfoNode node) {
-            param.add("FHIRPathTypeInfoNode: " + node.typeInfo());
+        public void visit(FHIRPathTypeInfoNode node) {
+            result.add("FHIRPathTypeInfoNode: " + node.typeInfo());
         }
     }
     
diff --git a/fhir-model/src/test/java/com/ibm/fhir/model/path/test/FHIRPathSpecTest.java b/fhir-model/src/test/java/com/ibm/fhir/model/path/test/FHIRPathSpecTest.java
index ac5ace1ed8b..6c340d062fa 100644
--- a/fhir-model/src/test/java/com/ibm/fhir/model/path/test/FHIRPathSpecTest.java
+++ b/fhir-model/src/test/java/com/ibm/fhir/model/path/test/FHIRPathSpecTest.java
@@ -30,11 +30,10 @@
 import org.testng.annotations.DataProvider;
 import org.testng.annotations.Factory;
 import org.testng.annotations.Test;
-
 import org.testng.internal.BaseTestMethod;
 
 import com.ibm.fhir.model.path.FHIRPathNode;
-import com.ibm.fhir.model.path.FHIRPathQuantityNode;
+import com.ibm.fhir.model.path.FHIRPathQuantityValue;
 import com.ibm.fhir.model.path.evaluator.FHIRPathEvaluator;
 import com.ibm.fhir.model.path.evaluator.FHIRPathEvaluator.EvaluationContext;
 import com.ibm.fhir.model.path.exception.FHIRPathException;
@@ -129,7 +128,7 @@ private void executeTest() throws Exception {
                 assertEquals(getNumberValue(singleton(result)).toString(), expectedOutput.text);
                 break;
             case "quantity":
-                assertEquals(result.as(FHIRPathQuantityNode.class).toString(), expectedOutput.text);
+                assertEquals(result.as(FHIRPathQuantityValue.class).toString(), expectedOutput.text);
                 break;
             case "string":
                 assertEquals(getStringValue(singleton(result)).toString(), expectedOutput.text);
diff --git a/fhir-model/src/test/java/com/ibm/fhir/model/path/test/NodeVisitorTest.java b/fhir-model/src/test/java/com/ibm/fhir/model/path/test/NodeVisitorTest.java
index 3c0809245c1..19a815f0ca7 100644
--- a/fhir-model/src/test/java/com/ibm/fhir/model/path/test/NodeVisitorTest.java
+++ b/fhir-model/src/test/java/com/ibm/fhir/model/path/test/NodeVisitorTest.java
@@ -17,10 +17,9 @@
 import com.ibm.fhir.model.format.Format;
 import com.ibm.fhir.model.parser.FHIRParser;
 import com.ibm.fhir.model.path.FHIRPathElementNode;
-import com.ibm.fhir.model.path.FHIRPathQuantityNode;
 import com.ibm.fhir.model.path.FHIRPathResourceNode;
 import com.ibm.fhir.model.path.FHIRPathTree;
-import com.ibm.fhir.model.path.visitor.FHIRPathNodeVisitorAdapter;
+import com.ibm.fhir.model.path.visitor.FHIRPathDefaultNodeVisitor;
 import com.ibm.fhir.model.resource.Patient;
 import com.ibm.fhir.model.resource.Resource;
 import com.ibm.fhir.model.type.Element;
@@ -47,19 +46,14 @@ public void doVisitStart(String elementName, int elementIndex, Element element)
                         
             List<String> treePaths = new ArrayList<>();
             FHIRPathTree tree = FHIRPathTree.tree(patient);
-            tree.getRoot().accept(new FHIRPathNodeVisitorAdapter<Void>() {
+            tree.getRoot().accept(new FHIRPathDefaultNodeVisitor() {
                 @Override
-                protected void doVisit(Void param, FHIRPathElementNode node) {
+                public void doVisit(FHIRPathElementNode node) {
                     treePaths.add(node.path());
                 }
 
                 @Override
-                protected void doVisit(Void param, FHIRPathQuantityNode node) {
-                    treePaths.add(node.path());
-                }
-
-                @Override
-                protected void doVisit(Void param, FHIRPathResourceNode node) {
+                public void doVisit(FHIRPathResourceNode node) {
                     treePaths.add(node.path());
                 }
             });
diff --git a/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/JDBCConstants.java b/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/JDBCConstants.java
index 20b0338137c..82998d43626 100644
--- a/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/JDBCConstants.java
+++ b/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/JDBCConstants.java
@@ -41,6 +41,9 @@ public class JDBCConstants {
     public static final String ESCAPE_UNDERSCORE = ESCAPE_CHAR + "_";
     public static final String ESCAPE_PERCENT = ESCAPE_CHAR + PERCENT_WILDCARD;
     public static final String ESCAPE_EXPR = " ESCAPE '" + ESCAPE_CHAR + "'";
+    public static final String WHEN = " WHEN ";
+    public static final String THEN = " THEN ";
+    public static final String END = " END";
     
     /**
      * Maps Parameter modifiers to SQL operators.
diff --git a/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/dao/api/ResourceDAO.java b/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/dao/api/ResourceDAO.java
index 1eba8cd9a23..dd7320ad6ad 100644
--- a/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/dao/api/ResourceDAO.java
+++ b/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/dao/api/ResourceDAO.java
@@ -118,19 +118,18 @@ List<Resource> search(String sqlSelect)
      * @throws FHIRPersistenceDataAccessException
      * @throws FHIRPersistenceDBConnectException
      */
-    List<Long> searchForIds(String sqlSelect)
-            throws FHIRPersistenceDataAccessException, FHIRPersistenceDBConnectException;
+    List<Long> searchForIds(SqlQueryData  queryData) throws FHIRPersistenceDataAccessException, FHIRPersistenceDBConnectException;
 
     /**
      * Searches for Resources that contain one of the passed ids.
+     * @param resourceType - The type of the FHIR Resource
      * @param resourceIds - A List of resource ids.
      * @return List<Resource> - A List of resources matching the the passed list of ids.
      * @throws FHIRPersistenceDataAccessException
      * @throws FHIRPersistenceDBConnectException
      */
-    List<Resource> searchByIds(List<Long> resourceIds)
-            throws FHIRPersistenceDataAccessException, FHIRPersistenceDBConnectException;
-    
+    List<Resource> searchByIds(String resourceType, List<Long> resourceIds) throws FHIRPersistenceDataAccessException, FHIRPersistenceDBConnectException;
+
     /**
      * Executes a count query based on the data contained in the passed SqlQueryData, using it's encapsulated search string and bind variables.
      * @param queryData - Contains a search string and (optionally) bind variables.
@@ -173,27 +172,6 @@ List<Resource> searchByIds(List<Long> resourceIds)
      * @throws FHIRPersistenceDataAccessException
      */
     Integer readResourceTypeId(String parameterName) throws FHIRPersistenceDBConnectException, FHIRPersistenceDataAccessException;
-    
-    /**
-     * This method supports the execution of a specialized query designed to return Resource ids, based on the contents
-     * of the passed select statement.
-     * Note that the first column to be selected MUST be the Resource.id column.
-     * @param sqlSelect - A select for Resource ids.
-     * @return - A List of resource ids that satisfy the passed SQL query.
-     * @throws FHIRPersistenceDataAccessException
-     * @throws FHIRPersistenceDBConnectException
-     */
-    List<Long> searchForIds(SqlQueryData  queryData) throws FHIRPersistenceDataAccessException, FHIRPersistenceDBConnectException;
-    
-    /**
-     * Searches for Resources that contain one of the passed ids.
-     * @param resourceType - The type of the FHIR Resource.
-     * @param resourceIds - A List of resource ids.
-     * @return List<Resource> - A List of resources matching the the passed list of ids.
-     * @throws FHIRPersistenceDataAccessException
-     * @throws FHIRPersistenceDBConnectException
-     */
-    List<Resource> searchByIds(String resourceType, List<Long> resourceIds) throws FHIRPersistenceDataAccessException, FHIRPersistenceDBConnectException;
 
     /**
      * Adds a resource type / resource id pair to a candidate collection for population into the ResourceTypesCache. 
diff --git a/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/dao/impl/ResourceDAOImpl.java b/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/dao/impl/ResourceDAOImpl.java
index 4483aa32b4b..9e20cc2106e 100644
--- a/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/dao/impl/ResourceDAOImpl.java
+++ b/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/dao/impl/ResourceDAOImpl.java
@@ -6,6 +6,8 @@
 
 package com.ibm.fhir.persistence.jdbc.dao.impl;
 
+import static com.ibm.fhir.persistence.jdbc.JDBCConstants.*;
+
 import java.sql.CallableStatement;
 import java.sql.Connection;
 import java.sql.PreparedStatement;
@@ -90,6 +92,8 @@ public class ResourceDAOImpl extends FHIRDbDAOImpl implements ResourceDAO {
                                                     "FROM %s_RESOURCES R, %s_LOGICAL_RESOURCES LR WHERE R.LOGICAL_RESOURCE_ID = LR.LOGICAL_RESOURCE_ID AND " +
                                                     "R.RESOURCE_ID IN ";
     
+    private static final String SQL_ORDER_BY_IDS = "ORDER BY CASE R.RESOURCE_ID ";
+    
     private static final String DERBY_PAGINATION_PARMS = "OFFSET ? ROWS FETCH NEXT ? ROWS ONLY";
     
     private static final String DB2_PAGINATION_PARMS = "LIMIT ? OFFSET ?";
@@ -418,64 +422,7 @@ public List<Long> searchForIds(SqlQueryData queryData) throws FHIRPersistenceDat
         return resourceIds;
     }
 
-    @Override
-    public List<Resource> searchByIds(String resourceType, List<Long> resourceIds) throws FHIRPersistenceDataAccessException, FHIRPersistenceDBConnectException {
-        final String METHODNAME = "searchByIds";
-        log.entering(CLASSNAME, METHODNAME);
-        
-        if (resourceIds.isEmpty()) {
-            return Collections.emptyList();
-        }
-
-        Connection connection = null;
-        PreparedStatement stmt = null;
-        ResultSet resultSet = null;
-        String errMsg;
-        StringBuilder idQuery = new StringBuilder();
-        List<Resource> resources = new ArrayList<>();
-        String stmtString = null;
-        long dbCallStartTime;
-        double dbCallDuration;
-
-        try {
-            stmtString = String.format(this.getSearchByIdsSql(resourceType));
-            idQuery.append(stmtString);
-            idQuery.append("(");
-            for (int i = 0; i < resourceIds.size(); i++) {
-                if (i > 0) {
-                    idQuery.append(",");
-                }
-                idQuery.append(resourceIds.get(i));
-            }
-            idQuery.append(")");
-
-            connection = this.getConnection();
-            stmt = connection.prepareStatement(idQuery.toString());
-            dbCallStartTime = System.nanoTime();
-            resultSet = stmt.executeQuery();
-            dbCallDuration = (System.nanoTime()-dbCallStartTime)/1e6;
-            if (log.isLoggable(Level.FINE)) {
-                log.fine("DB search by ids complete. SQL=[" + idQuery + "]  executionTime=" + dbCallDuration + "ms");
-            }
-            resources = this.createDTOs(resultSet);
-        } catch(FHIRPersistenceException e) {
-            throw e;
-        } catch (Throwable e) {
-            FHIRPersistenceDataAccessException fx = new FHIRPersistenceDataAccessException("Failure retrieving FHIR Resources");
-            errMsg = "Failure retrieving FHIR Resources. SQL=[" + idQuery + "]";
-            throw severe(log, fx, errMsg, e);
-        } finally {
-            this.cleanup(resultSet, stmt, connection);
-            log.exiting(CLASSNAME, METHODNAME);
-        }
-        return resources;
-    }
-
-    protected String getSearchByIdsSql(String resourceType) {
-        String stmtString;
-        stmtString = String.format(SQL_SEARCH_BY_IDS, resourceType, resourceType);
-        return stmtString;
-    }
+    
 
      /**
      * Adds a resource type/ resource id pair to a candidate collection for population into the ResourceTypesCache.
@@ -734,78 +681,55 @@ public List<Resource> search(String sqlSelect) throws FHIRPersistenceDataAccessE
     }
 
     @Override
-    public List<Long> searchForIds(String sqlSelect) throws FHIRPersistenceDataAccessException, FHIRPersistenceDBConnectException {
-        final String METHODNAME = "searchForIds";
-        log.entering(CLASSNAME, METHODNAME);
-        
-        List<Long> resourceIds = new ArrayList<>();
-        Connection connection = null;
-        PreparedStatement stmt = null;
-        ResultSet resultSet = null;
-        String errMsg;
-        
-        try {
-            connection = this.getConnection();
-            stmt = connection.prepareStatement(sqlSelect);
-            resultSet = stmt.executeQuery();
-            while (resultSet.next()) {
-                resourceIds.add(resultSet.getLong(1));
-            }
-        } catch(FHIRPersistenceException e) {
-            throw e;
-        } catch (Throwable e) {
-            // Log the SQL but don't expose it in the exception
-            FHIRPersistenceDataAccessException fx = new FHIRPersistenceDataAccessException("Failure retrieving FHIR Resource Ids.");
-            errMsg = "Failure retrieving FHIR Resource Ids. SQL=" + sqlSelect;
-            throw severe(log, fx, errMsg, e);
-        } finally {
-            this.cleanup(resultSet, stmt, connection);
-            log.exiting(CLASSNAME, METHODNAME);
-        }
-        return resourceIds;
-    }
-
-    @Override
-    public List<Resource> searchByIds(List<Long> resourceIds) throws FHIRPersistenceDataAccessException, FHIRPersistenceDBConnectException {
+    public List<Resource> searchByIds(String resourceType, List<Long> resourceIds) throws FHIRPersistenceDataAccessException, FHIRPersistenceDBConnectException {
         final String METHODNAME = "searchByIds";
         log.entering(CLASSNAME, METHODNAME);
         
         if (resourceIds.isEmpty()) {
             return Collections.emptyList();
         }
-        
+
         Connection connection = null;
         PreparedStatement stmt = null;
         ResultSet resultSet = null;
         String errMsg;
         StringBuilder idQuery = new StringBuilder();
         List<Resource> resources = new ArrayList<>();
-        
+        String stmtString = null;
+        long dbCallStartTime;
+        double dbCallDuration;
+
         try {
-            idQuery.append(SQL_SEARCH_BY_IDS);
+            stmtString = getSearchByIdsSql(resourceType);
+            idQuery.append(stmtString);
             idQuery.append("(");
+            // resourceIds should have a max length of 1000 (the max page size)
+            StringBuilder caseStmts = new StringBuilder();
             for (int i = 0; i < resourceIds.size(); i++) {
                 if (i > 0) {
                     idQuery.append(",");
                 }
-                idQuery.append("?");
+                idQuery.append(resourceIds.get(i));
+                
+                // build up the caseStmts here so we only need to iterate the list once
+                caseStmts.append(WHEN + resourceIds.get(i) + THEN + i);
             }
-            idQuery.append(")");
-                        
+            idQuery.append(") " + SQL_ORDER_BY_IDS + caseStmts + END);
+
             connection = this.getConnection();
             stmt = connection.prepareStatement(idQuery.toString());
-            // Inject IDs into the prepared stmt.
-            for (int i = 0; i < resourceIds.size(); i++) {
-                stmt.setObject(i+1, resourceIds.get(i));
-            }
+            dbCallStartTime = System.nanoTime();
             resultSet = stmt.executeQuery();
+            dbCallDuration = (System.nanoTime()-dbCallStartTime)/1e6;
+            if (log.isLoggable(Level.FINE)) {
+                log.fine("DB search by ids complete. SQL=[" + idQuery + "]  executionTime=" + dbCallDuration + "ms");
+            }
             resources = this.createDTOs(resultSet);
         } catch(FHIRPersistenceException e) {
             throw e;
         } catch (Throwable e) {
-            // Log the SQL but don't expose it in the exception
-            FHIRPersistenceDataAccessException fx = new FHIRPersistenceDataAccessException("Failure retrieving FHIR Resources.");
-            errMsg = "Failure retrieving FHIR Resources. SQL=" + idQuery;
+            FHIRPersistenceDataAccessException fx = new FHIRPersistenceDataAccessException("Failure retrieving FHIR Resources");
+            errMsg = "Failure retrieving FHIR Resources. SQL=[" + idQuery + "]";
             throw severe(log, fx, errMsg, e);
         } finally {
             this.cleanup(resultSet, stmt, connection);
@@ -814,6 +738,10 @@ public List<Resource> searchByIds(List<Long> resourceIds) throws FHIRPersistence
         return resources;
     }
 
+    protected String getSearchByIdsSql(String resourceType) {
+        return String.format(SQL_SEARCH_BY_IDS, resourceType, resourceType);
+    }
+
     @Override
     public int searchCount(String sqlSelectCount) throws FHIRPersistenceDataAccessException, FHIRPersistenceDBConnectException {
         final String METHODNAME = "searchCount";
diff --git a/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/impl/FHIRPersistenceJDBCImpl.java b/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/impl/FHIRPersistenceJDBCImpl.java
index 200783cfc01..2ce67af5acc 100644
--- a/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/impl/FHIRPersistenceJDBCImpl.java
+++ b/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/impl/FHIRPersistenceJDBCImpl.java
@@ -50,7 +50,7 @@
 import com.ibm.fhir.model.parser.FHIRJsonParser;
 import com.ibm.fhir.model.parser.FHIRParser;
 import com.ibm.fhir.model.path.FHIRPathNode;
-import com.ibm.fhir.model.path.FHIRPathPrimitiveValue;
+import com.ibm.fhir.model.path.FHIRPathSystemValue;
 import com.ibm.fhir.model.resource.OperationOutcome;
 import com.ibm.fhir.model.resource.Resource;
 import com.ibm.fhir.model.resource.SearchParameter;
@@ -1020,8 +1020,8 @@ private List<Parameter> extractSearchParameters(Resource fhirResource, com.ibm.f
                         if (value.isElementNode()) {
                             // parameterBuilder aggregates the results for later retrieval
                             value.asElementNode().element().accept(parameterBuilder);
-                        } else if (value.isPrimitiveValue()){
-                            Parameter p = processPrimitiveValue(value.asPrimitiveValue());
+                        } else if (value.isSystemValue()){
+                            Parameter p = processPrimitiveValue(value.asSystemValue());
                             p.setName(code);
                             p.setType(Type.fromValue(type));
                             p.setResourceId(resourceDTO.getId());
@@ -1076,22 +1076,20 @@ private List<Parameter> extractSearchParameters(Resource fhirResource, com.ibm.f
      * Note: this method only sets the value; 
      * caller is responsible for setting all other fields on the created Parameter.
      */
-    private Parameter processPrimitiveValue(FHIRPathPrimitiveValue primitiveValue) {
+    private Parameter processPrimitiveValue(FHIRPathSystemValue systemValue) {
         Parameter p = new Parameter();
-        if (primitiveValue.isBooleanValue()) {
-            if (primitiveValue.asBooleanValue()._boolean()) {
+        if (systemValue.isBooleanValue()) {
+            if (systemValue.asBooleanValue()._boolean()) {
                 p.setValueCode("true");
             } else {
                 p.setValueCode("false");
             }
-        } else if (primitiveValue.isDateTimeValue()) {
-            p.setValueDate(Timestamp.from(QueryBuilderUtil.getInstantFromPartial(primitiveValue.asDateTimeValue().dateTime())));
-        } else if (primitiveValue.isStringValue()) {
-            p.setValueString(primitiveValue.asStringValue().string());
-        } else if (primitiveValue.isTimeValue()) {
-            p.setValueDate(Timestamp.from(QueryBuilderUtil.getInstantFromPartial(primitiveValue.asTimeValue().time())));
-        } else if (primitiveValue.isNumberValue()) {
-            p.setValueNumber(primitiveValue.asNumberValue().decimal());
+        } else if (systemValue.isTemporalValue()) {
+            p.setValueDate(Timestamp.from(QueryBuilderUtil.getInstantFromPartial(systemValue.asTemporalValue().temporal())));
+        } else if (systemValue.isStringValue()) {
+            p.setValueString(systemValue.asStringValue().string());
+        } else if (systemValue.isNumberValue()) {
+            p.setValueNumber(systemValue.asNumberValue().decimal());
         }
         return p;
     }
diff --git a/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/util/SortedQuerySegmentAggregator.java b/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/util/SortedQuerySegmentAggregator.java
index cdc03c70490..bed4442dc60 100644
--- a/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/util/SortedQuerySegmentAggregator.java
+++ b/fhir-persistence-jdbc/src/main/java/com/ibm/fhir/persistence/jdbc/util/SortedQuerySegmentAggregator.java
@@ -57,15 +57,14 @@ protected SortedQuerySegmentAggregator(Class<?> resourceType, int offset, int pa
      * <p>
      * A simple example query produced by this method:
      * <pre>
-     * SELECT R.RESOURCE_ID,MIN(S1.STR_VALUE) FROM 
-     * Patient_RESOURCES R JOIN 
-     * Patient_LOGICAL_RESOURCES LR ON R.LOGICAL_RESOURCE_ID=LR.LOGICAL_RESOURCE_ID  JOIN 
-     * Patient_TOKEN_VALUES P1 ON P1.RESOURCE_ID=R.RESOURCE_ID  
-     * LEFT OUTER JOIN Patient_STR_VALUES S1 ON (S1.PARAMETER_NAME_ID=50 AND S1.RESOURCE_ID = R.RESOURCE_ID) WHERE 
-     * R.RESOURCE_ID = LR.CURRENT_RESOURCE_ID AND 
-     * R.IS_DELETED <> 'Y' AND 
-     * P1.RESOURCE_ID = R.RESOURCE_ID AND 
-     * (P1.PARAMETER_NAME_ID=196 AND ((P1.TOKEN_VALUE = false))) 
+     * SELECT R.RESOURCE_ID,MIN(S1.STR_VALUE) FROM Patient_RESOURCES R 
+     *   JOIN Patient_LOGICAL_RESOURCES LR ON R.LOGICAL_RESOURCE_ID=LR.LOGICAL_RESOURCE_ID
+     *   JOIN Patient_TOKEN_VALUES P1 ON P1.RESOURCE_ID=R.RESOURCE_ID  
+     *   LEFT OUTER JOIN Patient_STR_VALUES S1 ON (S1.PARAMETER_NAME_ID=50 AND S1.RESOURCE_ID = R.RESOURCE_ID)
+     *   WHERE R.RESOURCE_ID = LR.CURRENT_RESOURCE_ID AND 
+     *         R.IS_DELETED <> 'Y' AND 
+     *         P1.RESOURCE_ID = R.RESOURCE_ID AND 
+     *         (P1.PARAMETER_NAME_ID=196 AND ((P1.TOKEN_VALUE = false))) 
      * GROUP BY R.RESOURCE_ID  
      * ORDER BY MIN(S1.STR_VALUE) asc NULLS LAST 
      * OFFSET 0 ROWS FETCH NEXT 100 ROWS ONLY;
diff --git a/fhir-persistence/src/main/java/com/ibm/fhir/persistence/util/Processor.java b/fhir-persistence/src/main/java/com/ibm/fhir/persistence/util/Processor.java
index 713ce52faaa..4e684b327d3 100644
--- a/fhir-persistence/src/main/java/com/ibm/fhir/persistence/util/Processor.java
+++ b/fhir-persistence/src/main/java/com/ibm/fhir/persistence/util/Processor.java
@@ -18,7 +18,7 @@
 import com.ibm.fhir.model.path.FHIRPathDecimalValue;
 import com.ibm.fhir.model.path.FHIRPathElementNode;
 import com.ibm.fhir.model.path.FHIRPathIntegerValue;
-import com.ibm.fhir.model.path.FHIRPathQuantityNode;
+import com.ibm.fhir.model.path.FHIRPathQuantityValue;
 import com.ibm.fhir.model.path.FHIRPathResourceNode;
 import com.ibm.fhir.model.path.FHIRPathStringValue;
 import com.ibm.fhir.model.path.FHIRPathTimeValue;
@@ -193,7 +193,7 @@ public interface Processor<T> {
 
     T process(SearchParameter parameter, FHIRPathBooleanValue value) throws FHIRPersistenceProcessorException;
 
-    T process(SearchParameter parameter, FHIRPathQuantityNode value) throws FHIRPersistenceProcessorException;
+    T process(SearchParameter parameter, FHIRPathQuantityValue value) throws FHIRPersistenceProcessorException;
 
     T process(SearchParameter parameter, ZonedDateTime value) throws FHIRPersistenceProcessorException;
 
diff --git a/fhir-persistence/src/test/java/com/ibm/fhir/persistence/test/ProcessorTest.java b/fhir-persistence/src/test/java/com/ibm/fhir/persistence/test/ProcessorTest.java
index 3eecb126490..8c91288ea4b 100644
--- a/fhir-persistence/src/test/java/com/ibm/fhir/persistence/test/ProcessorTest.java
+++ b/fhir-persistence/src/test/java/com/ibm/fhir/persistence/test/ProcessorTest.java
@@ -22,7 +22,7 @@
 import com.ibm.fhir.model.path.FHIRPathDecimalValue;
 import com.ibm.fhir.model.path.FHIRPathElementNode;
 import com.ibm.fhir.model.path.FHIRPathIntegerValue;
-import com.ibm.fhir.model.path.FHIRPathQuantityNode;
+import com.ibm.fhir.model.path.FHIRPathQuantityValue;
 import com.ibm.fhir.model.path.FHIRPathResourceNode;
 import com.ibm.fhir.model.path.FHIRPathStringValue;
 import com.ibm.fhir.model.path.FHIRPathTimeValue;
@@ -406,8 +406,8 @@ public String process(SearchParameter parameter, YearMonth value) throws FHIRPer
         }
         
         @Override
-        public String process(SearchParameter parameter, FHIRPathQuantityNode value) throws FHIRPersistenceProcessorException {
-            return "process(SearchParameter, FHIRPathQuantityNode)";
+        public String process(SearchParameter parameter, FHIRPathQuantityValue value) throws FHIRPersistenceProcessorException {
+            return "process(SearchParameter, FHIRPathQuantityValue)";
         }
 
         @Override
diff --git a/fhir-search/src/test/java/com/ibm/fhir/search/test/ExtractorValidator.java b/fhir-search/src/test/java/com/ibm/fhir/search/test/ExtractorValidator.java
index 626dc5638fb..7e5b0ef3cc4 100644
--- a/fhir-search/src/test/java/com/ibm/fhir/search/test/ExtractorValidator.java
+++ b/fhir-search/src/test/java/com/ibm/fhir/search/test/ExtractorValidator.java
@@ -25,7 +25,7 @@
 import com.ibm.fhir.model.path.FHIRPathDateTimeValue;
 import com.ibm.fhir.model.path.FHIRPathElementNode;
 import com.ibm.fhir.model.path.FHIRPathNode;
-import com.ibm.fhir.model.path.FHIRPathPrimitiveValue;
+import com.ibm.fhir.model.path.FHIRPathSystemValue;
 import com.ibm.fhir.model.path.FHIRPathResourceNode;
 import com.ibm.fhir.model.path.FHIRPathStringValue;
 import com.ibm.fhir.model.resource.SearchParameter;
@@ -43,7 +43,7 @@ public void addExpected(String name, List<String> values) {
     }
 
     /**
-     * validates the FHIR Path expectations for a specific search parameter. 
+     * validates the FHIR Path expectations for a specific search parameter.
      * @param output
      */
     public void validate(Map<SearchParameter, List<FHIRPathNode>> output) {
@@ -117,7 +117,7 @@ private void printOutput(Map<SearchParameter, List<FHIRPathNode>> output) {
      * Process the FHIRPathNode into a String value
      */
     private static String processOutput(FHIRPathNode node) {
-        
+
         String val = "";
         if (node.getClass().getSimpleName().contains("FHIRPathBooleanValue")) {
             FHIRPathBooleanValue booleanValue = (FHIRPathBooleanValue) node;
@@ -127,11 +127,12 @@ private static String processOutput(FHIRPathNode node) {
                 val = "false";
             }
 
-        } else if (node.isPrimitiveValue()) {
-            FHIRPathPrimitiveValue nodeConverted = node.asPrimitiveValue();
-            if (nodeConverted.isDateTimeValue()) {
-                FHIRPathDateTimeValue v = (FHIRPathDateTimeValue) node;
-                val = "" + v.toString();
+        } else if (node.isSystemValue()) {
+            FHIRPathSystemValue nodeConverted = node.asSystemValue();
+            if (nodeConverted.isTemporalValue() && nodeConverted.asTemporalValue().isDateTimeValue()) {
+              FHIRPathDateTimeValue v = (FHIRPathDateTimeValue) nodeConverted.asTemporalValue();
+              val = "" + v.toString();
+
             } else if (nodeConverted.isStringValue()) {
                 FHIRPathStringValue v = nodeConverted.asStringValue();
                 val = "" + v.string();
@@ -140,14 +141,14 @@ private static String processOutput(FHIRPathNode node) {
         } else if (node.is(FHIRPathElementNode.class)) {
             FHIRPathElementNode tNode = node.asElementNode();
 
-            FHIRPathPrimitiveValue v = tNode.getValue();
+            FHIRPathSystemValue v = tNode.getValue();
             if (v != null) {
 
                 if (v.isStringValue()) {
                     FHIRPathStringValue sv = v.asStringValue();
                     val = "" + sv.string();
-                } else if (v.isDateTimeValue()) {
-                    FHIRPathDateTimeValue vv = v.asDateTimeValue();
+                } else if (v.isTemporalValue() && v.asTemporalValue().isDateTimeValue()) {
+                    FHIRPathDateTimeValue vv = v.asTemporalValue().asDateTimeValue();
                     TemporalAccessor acc = vv.dateTime();
                     val = "" + acc.toString(); //DATE_TIME_FORMATTER.format(acc);
                 }
@@ -158,8 +159,8 @@ private static String processOutput(FHIRPathNode node) {
                         FHIRPathElementNode nx = child.asElementNode();
                         val = "" + nx.getValue();
 
-                    } else if (child.isPrimitiveValue()) {
-                        FHIRPathPrimitiveValue v1 = child.asPrimitiveValue();
+                    } else if (child.isSystemValue()) {
+                        FHIRPathSystemValue v1 = child.asSystemValue();
                         if (v1.isStringValue()) {
                             FHIRPathStringValue sv = v1.asStringValue();
                             val = "" + sv.string() + ",";
diff --git a/fhir-server-test/src/test/java/com/ibm/fhir/server/test/SearchPerformaceTest.java b/fhir-server-test/src/test/java/com/ibm/fhir/server/test/SearchPerformaceTest.java
index a439e316d8a..66d60723b44 100644
--- a/fhir-server-test/src/test/java/com/ibm/fhir/server/test/SearchPerformaceTest.java
+++ b/fhir-server-test/src/test/java/com/ibm/fhir/server/test/SearchPerformaceTest.java
@@ -15,6 +15,7 @@
 import static org.testng.Assert.assertTrue;
 
 import java.lang.reflect.Method;
+import java.math.BigDecimal;
 import java.util.List;
 
 import javax.ws.rs.client.Entity;
@@ -27,9 +28,14 @@
 import com.ibm.fhir.model.resource.Bundle;
 import com.ibm.fhir.model.resource.Observation;
 import com.ibm.fhir.model.resource.Patient;
+import com.ibm.fhir.model.resource.Observation.Component;
 import com.ibm.fhir.model.test.TestUtil;
 import com.ibm.fhir.model.type.Code;
+import com.ibm.fhir.model.type.CodeableConcept;
 import com.ibm.fhir.model.type.Coding;
+import com.ibm.fhir.model.type.Decimal;
+import com.ibm.fhir.model.type.Quantity;
+import com.ibm.fhir.model.type.Uri;
 import com.ibm.fhir.model.type.code.AdministrativeGender;
 import com.ibm.fhir.model.util.FHIRUtil;
 
@@ -44,7 +50,7 @@ public class SearchPerformaceTest extends FHIRServerTestBase {
     // Controls how many observations and patients to create for the test.
     // Using invocationCount of testng can cause the testng report grows too big, so
     // this config is used to make sure all test users are created in one testng step.
-    private final int numOfPatientObservationsToCreate = 100;
+    private final int numOfPatientObservationsToCreate = 1000;
 
     /**
      * Retrieve the server's conformance statement to determine the status of certain runtime options.
@@ -87,6 +93,21 @@ public void testCreatePatientAndObservation() throws Exception {
             // create observation for the patient
             Observation observation =
                     TestUtil.buildPatientObservation(patientId, "Observation1.json");
+            observation = observation.toBuilder()
+                    .code(CodeableConcept.builder()
+                            .coding(Coding.builder()
+                                    .system(Uri.of("http://loinc.org"))
+                                    .code(Code.of("55284-4"))
+                                    .build())
+                            .build())
+                    .component(Component.builder()
+                            .code(CodeableConcept.builder().text(string("component1")).build())
+                            .value(Quantity.builder()
+                                    .value(Decimal.of(BigDecimal.valueOf(Math.random())))
+                                    .unit(string("mmHg"))
+                                    .build())
+                            .build())
+                    .build();
             Entity<Observation> entity2 =
                     Entity.entity(observation, FHIRMediaType.APPLICATION_FHIR_JSON);
             response =
diff --git a/fhir-server-test/src/test/java/com/ibm/fhir/server/test/SortingTest.java b/fhir-server-test/src/test/java/com/ibm/fhir/server/test/SortingTest.java
index 34f5ec9332d..b402b3047a8 100644
--- a/fhir-server-test/src/test/java/com/ibm/fhir/server/test/SortingTest.java
+++ b/fhir-server-test/src/test/java/com/ibm/fhir/server/test/SortingTest.java
@@ -674,6 +674,7 @@ private void assertTrueNaturalOrdering(List<BigDecimal> sortedList) {
                 }
 
                 assertTrue(prior.compareTo(current) <= 0);
+                prior = current;
             }
             done = true;
         }
diff --git a/fhir-validation/pom.xml b/fhir-validation/pom.xml
index cee259cd213..653719323a1 100644
--- a/fhir-validation/pom.xml
+++ b/fhir-validation/pom.xml
@@ -40,6 +40,12 @@
             <artifactId>fhir-examples</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>fhir-ig-us-core</artifactId>
+            <version>${project.version}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <profiles>
diff --git a/fhir-validation/src/main/java/com/ibm/fhir/validation/FHIRValidator.java b/fhir-validation/src/main/java/com/ibm/fhir/validation/FHIRValidator.java
index 034f81a8c26..299e035d84b 100644
--- a/fhir-validation/src/main/java/com/ibm/fhir/validation/FHIRValidator.java
+++ b/fhir-validation/src/main/java/com/ibm/fhir/validation/FHIRValidator.java
@@ -19,12 +19,11 @@
 import com.ibm.fhir.model.annotation.Constraint;
 import com.ibm.fhir.model.path.FHIRPathElementNode;
 import com.ibm.fhir.model.path.FHIRPathNode;
-import com.ibm.fhir.model.path.FHIRPathQuantityNode;
 import com.ibm.fhir.model.path.FHIRPathResourceNode;
 import com.ibm.fhir.model.path.FHIRPathTree;
 import com.ibm.fhir.model.path.evaluator.FHIRPathEvaluator;
 import com.ibm.fhir.model.path.evaluator.FHIRPathEvaluator.EvaluationContext;
-import com.ibm.fhir.model.path.visitor.FHIRPathVoidParameterNodeVisitorAdapter;
+import com.ibm.fhir.model.path.visitor.FHIRPathDefaultNodeVisitor;
 import com.ibm.fhir.model.resource.DomainResource;
 import com.ibm.fhir.model.resource.OperationOutcome.Issue;
 import com.ibm.fhir.model.resource.Resource;
@@ -143,7 +142,7 @@ public static FHIRValidator validator() {
         return new FHIRValidator();
     }
 
-    private static class ValidatingNodeVisitor extends FHIRPathVoidParameterNodeVisitorAdapter {
+    private static class ValidatingNodeVisitor extends FHIRPathDefaultNodeVisitor {
         private FHIRPathEvaluator evaluator = FHIRPathEvaluator.evaluator();
         private EvaluationContext evaluationContext;
         private boolean includeResourceAssertedProfiles;
@@ -166,17 +165,12 @@ private void reset() {
         }
         
         @Override
-        protected void doVisit(FHIRPathElementNode node) {
+        public void doVisit(FHIRPathElementNode node) {
             validate(node);
         }
         
         @Override
-        protected void doVisit(FHIRPathResourceNode node) {
-            validate(node);
-        }
-        
-        @Override
-        protected void doVisit(FHIRPathQuantityNode node) {
+        public void doVisit(FHIRPathResourceNode node) {
             validate(node);
         }
 
diff --git a/fhir-validation/src/main/java/com/ibm/fhir/validation/util/ConstraintGenerator.java b/fhir-validation/src/main/java/com/ibm/fhir/validation/util/ConstraintGenerator.java
index e9e4ff34d54..83a40f8edba 100644
--- a/fhir-validation/src/main/java/com/ibm/fhir/validation/util/ConstraintGenerator.java
+++ b/fhir-validation/src/main/java/com/ibm/fhir/validation/util/ConstraintGenerator.java
@@ -19,6 +19,10 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.StringJoiner;
+import java.util.logging.Handler;
+import java.util.logging.Level;
+import java.util.logging.LogRecord;
+import java.util.logging.Logger;
 
 import com.ibm.fhir.model.annotation.Constraint;
 import com.ibm.fhir.model.resource.StructureDefinition;
@@ -39,6 +43,8 @@
  * A class used to generate FHIRPath expressions from a profile
  */
 public class ConstraintGenerator {
+    private static final Logger log = Logger.getLogger(ConstraintGenerator.class.getName());
+    
     private final StructureDefinition profile;
     private final Tree tree;
 
@@ -56,12 +62,15 @@ public List<Constraint> generate() {
     
         int index = 1;
     
+        log.fine("Generated constraint expressions:");
         for (Node child : tree.root.children) {
             String expr = generate(child);
+            log.fine(expr);
             String description = "Constraint violation: " + expr;
             constraints.add(constraint("generated-" + prefix + "-" + index, expr, description));
             index++;
         }
+        log.fine("");
     
         return constraints;
     }
@@ -100,25 +109,29 @@ private Tree buildTree(StructureDefinition profile) {
         tree.nodeMap = nodeMap;
         tree.sliceDefinitionMap = sliceDefinitionMap;
         
-        System.out.println("Paths before pruning:");
-        for (String path : nodeMap.keySet()) {
-            System.out.println("path: " + path);
+        if (log.isLoggable(Level.FINE)) {
+            log.fine("Element definitions BEFORE pruning:");
+            for (String id : nodeMap.keySet()) {
+                log.fine(id);
+            }
+            log.fine("");
         }
-        System.out.println("");
 
         prune(tree);
 
-        System.out.println("Paths after pruning:");
-        for (String path : nodeMap.keySet()) {
-            System.out.println("path: " + path);
-        }
-        System.out.println("");
-
-        System.out.println("Slice definitions:");
-        for (String id : sliceDefinitionMap.keySet()) {
-            System.out.println("id: " + id);
+        if (log.isLoggable(Level.FINE)) {
+            log.fine("Element definitions AFTER pruning:");
+            for (String id : nodeMap.keySet()) {
+                log.fine(id);
+            }
+            log.fine("");
+    
+            log.fine("Slice definitions:");
+            for (String id : sliceDefinitionMap.keySet()) {
+                log.fine(id);
+            }
+            log.fine("");
         }
-        System.out.println("");
 
         return tree;
     }
@@ -190,7 +203,11 @@ private String generate(Node node) {
                 if (isExtensionUrl(child.elementDefinition)) {
                     continue;
                 }
-                joiner.add(generate(child));
+                if (isOptional(child.elementDefinition)) {
+                    joiner.add("(" + generate(child) + ")");
+                } else {
+                    joiner.add(generate(child));
+                }
             }
             sb.append(joiner.toString());
             sb.append(")");
@@ -583,8 +600,25 @@ static class Tree {
     }
 
     public static void main(String[] args) throws Exception {
-        StructureDefinition profile = FHIRRegistry.getInstance().getResource("http://hl7.org/fhir/StructureDefinition/bp", StructureDefinition.class);
+        Logger logger = Logger.getLogger("");
+        logger.setLevel(Level.FINE);
+        logger.addHandler(new Handler() {
+            @Override
+            public void publish(LogRecord record) {
+                System.out.println(record.getMessage());
+            }
+
+            @Override
+            public void flush() {                
+            }
+
+            @Override
+            public void close() throws SecurityException {                
+            }
+        });
+        StructureDefinition profile = FHIRRegistry.getInstance().getResource("http://hl7.org/fhir/StructureDefinition/bodyweight", StructureDefinition.class);
         ConstraintGenerator generator = new ConstraintGenerator(profile);
+        System.out.println("Generated constraints: ");
         generator.generate().stream().map(constraint -> constraint.expression()).forEach(System.out::println);
     }
 }
\ No newline at end of file
diff --git a/fhir-validation/src/main/java/com/ibm/fhir/validation/util/ProfileSupport.java b/fhir-validation/src/main/java/com/ibm/fhir/validation/util/ProfileSupport.java
index c720d355f0f..260735e2dda 100644
--- a/fhir-validation/src/main/java/com/ibm/fhir/validation/util/ProfileSupport.java
+++ b/fhir-validation/src/main/java/com/ibm/fhir/validation/util/ProfileSupport.java
@@ -76,6 +76,8 @@ private static List<Constraint> computeConstraints(StructureDefinition profile,
             }
         }
         Collections.sort(constraints, CONSTRAINT_COMPARATOR);
+        ConstraintGenerator generator = new ConstraintGenerator(profile);
+        constraints.addAll(generator.generate());
         return constraints;
     }
 
@@ -180,7 +182,6 @@ public static List<Constraint> getConstraints(List<String> urls, Class<?> resour
     }
     
     public static List<Constraint> getConstraints(Resource resource) {
-        List<Constraint> constraints = new ArrayList<>();
         Meta meta = resource.getMeta();
         if (meta != null) {
             List<String> urls = new ArrayList<>();
@@ -191,7 +192,7 @@ public static List<Constraint> getConstraints(Resource resource) {
             }
             return getConstraints(urls, resource.getClass());
         }
-        return constraints;
+        return Collections.emptyList();
     }
 
     public static List<Constraint> getConstraints(String url, Class<?> resourceType) {
diff --git a/fhir-validation/src/test/java/com/ibm/fhir/validation/test/BloodPressureObservationTest.java b/fhir-validation/src/test/java/com/ibm/fhir/validation/test/BloodPressureObservationTest.java
new file mode 100644
index 00000000000..084d8be276e
--- /dev/null
+++ b/fhir-validation/src/test/java/com/ibm/fhir/validation/test/BloodPressureObservationTest.java
@@ -0,0 +1,142 @@
+/*
+ * (C) Copyright IBM Corp. 2019
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.ibm.fhir.validation.test;
+
+import static com.ibm.fhir.model.type.String.string;
+
+import java.util.List;
+import java.util.logging.Handler;
+import java.util.logging.Level;
+import java.util.logging.LogRecord;
+import java.util.logging.Logger;
+
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+import com.ibm.fhir.model.format.Format;
+import com.ibm.fhir.model.generator.FHIRGenerator;
+import com.ibm.fhir.model.resource.Observation;
+import com.ibm.fhir.model.resource.Observation.Component;
+import com.ibm.fhir.model.resource.OperationOutcome.Issue;
+import com.ibm.fhir.model.type.Canonical;
+import com.ibm.fhir.model.type.Code;
+import com.ibm.fhir.model.type.CodeableConcept;
+import com.ibm.fhir.model.type.Coding;
+import com.ibm.fhir.model.type.DateTime;
+import com.ibm.fhir.model.type.Decimal;
+import com.ibm.fhir.model.type.Meta;
+import com.ibm.fhir.model.type.Quantity;
+import com.ibm.fhir.model.type.Reference;
+import com.ibm.fhir.model.type.Uri;
+import com.ibm.fhir.model.type.code.ObservationStatus;
+import com.ibm.fhir.validation.FHIRValidator;
+
+public class BloodPressureObservationTest {
+    @Test
+    public static void testBloodPressureObservation() throws Exception {
+        // build a blood pressure observation
+        Observation bloodPressureObservation = Observation.builder()
+            // resource metadata
+            .meta(Meta.builder()
+                // asssert conformance to the blood pressure profile
+                .profile(Canonical.of("http://hl7.org/fhir/StructureDefinition/bp"))
+                .build())
+            
+            // observation status
+            .status(ObservationStatus.FINAL)
+            
+            // observation subject (Patient)
+            .subject(Reference.builder()
+                .reference(string("Patient/1234"))
+                .build())
+            
+            // observation effective time
+            .effective(DateTime.builder()
+                .value("2019-01-01")
+                .build())
+                        
+            // observation category (vital signs)
+            .category(CodeableConcept.builder()
+                .coding(Coding.builder()
+                    .system(Uri.of("http://terminology.hl7.org/CodeSystem/observation-category"))
+                    .code(Code.of("vital-signs"))
+                    .build())
+                .build())
+            
+            // observation code (blood pressure)
+            .code(CodeableConcept.builder()
+                .coding(Coding.builder()
+                    .system(Uri.of("http://loinc.org"))
+                    .code(Code.of("85354-9"))
+                    .build())
+                .build())
+            
+            // observation component (systolic blood pressure)
+            .component(Component.builder()
+                .code(CodeableConcept.builder()
+                    .coding(Coding.builder()
+                        .system(Uri.of("http://loinc.org"))
+//                      .code(Code.of("8480-6"))
+                        .display(string("Systolic Blood Pressure"))
+                        .build())
+                    .build())
+                .value(Quantity.builder()
+                    .value(Decimal.of(120))
+                    .system(Uri.of("http://unitsofmeasure.org"))
+                    .code(Code.of("mm[Hg]"))
+                    .unit(string("mm[Hg]"))
+                    .build())
+                .build())
+            
+            // observation component (diastolic blood pressure)
+            .component(Component.builder()
+                .code(CodeableConcept.builder()
+                    .coding(Coding.builder()
+                        .system(Uri.of("http://loinc.org"))
+                        .code(Code.of("8462-4"))
+                        .display(string("Diastolic Blood Pressure"))
+                        .build())
+                    .build())
+                .value(Quantity.builder()
+                    .value(Decimal.of(80))
+                    .system(Uri.of("http://unitsofmeasure.org"))
+                    .code(Code.of("mm[Hg]"))
+                    .unit(string("mm[Hg]"))
+                    .build())
+                .build())
+            .build();
+        
+        // print the blood pressure observation to the console
+        FHIRGenerator.generator(Format.JSON, true).generate(bloodPressureObservation, System.out);
+        System.out.println("");
+        
+        // validate the blood pressure observation in debug mode and print issues to console
+        Logger logger = Logger.getLogger("");
+        logger.setLevel(Level.FINE);
+        logger.addHandler(new Handler() {
+            @Override
+            public void publish(LogRecord record) {
+                System.out.println(record.getMessage());
+            }
+
+            @Override
+            public void flush() {                
+            }
+
+            @Override
+            public void close() throws SecurityException {                
+            }
+        });
+        List<Issue> issues = FHIRValidator.validator().validate(bloodPressureObservation);
+        issues.forEach(System.out::println);
+        Assert.assertEquals(issues.size(), 2);
+        Assert.assertTrue(issues.get(0).getDetails().getText().getValue().startsWith("dom-6"));
+        Assert.assertTrue(issues.get(1).getDetails().getText().getValue().startsWith("generated-bp-8"));
+
+        System.out.println("");
+    }
+}
\ No newline at end of file
diff --git a/fhir-validation/src/test/java/com/ibm/fhir/validation/test/BodyWeightProfileTest.java b/fhir-validation/src/test/java/com/ibm/fhir/validation/test/BodyWeightProfileTest.java
index 98270ff60f8..122ea284a6f 100644
--- a/fhir-validation/src/test/java/com/ibm/fhir/validation/test/BodyWeightProfileTest.java
+++ b/fhir-validation/src/test/java/com/ibm/fhir/validation/test/BodyWeightProfileTest.java
@@ -36,7 +36,7 @@ public class BodyWeightProfileTest {
     public static void testBodyWeightProfile() throws Exception {
         List<Constraint> constraints = getConstraints(BODY_WEIGHT_PROFILE_URL, Observation.class);
 
-        Assert.assertEquals(constraints.size(), 3);
+        Assert.assertEquals(constraints.size(), 10);
         Assert.assertTrue(constraints.stream().filter(constraint -> constraint.id().equals("vs-1")).count() == 1);
         Assert.assertTrue(constraints.stream().filter(constraint -> constraint.id().equals("vs-2")).count() == 1);
         Assert.assertTrue(constraints.stream().filter(constraint -> constraint.id().equals("vs-3")).count() == 1);
@@ -76,10 +76,14 @@ public static void testBodyWeightProfile() throws Exception {
                 .build();
 
         List<Issue> issues = FHIRValidator.validator().validate(bodyWeight);
-        Assert.assertEquals(issues.size(), 2);
+        
+        issues.forEach(System.out::println);
+        
+        Assert.assertEquals(issues.size(), 3);
         Assert.assertTrue(issues.stream().filter(issue -> issue.getDetails().getText().getValue().startsWith("dom-6")).count() == 1);
         Assert.assertTrue(issues.stream().filter(issue -> issue.getDetails().getText().getValue().startsWith("vs-1")).count() == 1);
-        
+        Assert.assertTrue(issues.stream().filter(issue -> issue.getDetails().getText().getValue().startsWith("generated-bodyweight-3")).count() == 1);
+
         bodyWeight = bodyWeight.toBuilder()
                 .meta(null)
                 .build();
@@ -89,7 +93,7 @@ public static void testBodyWeightProfile() throws Exception {
         Assert.assertTrue(issues.stream().filter(issue -> issue.getDetails().getText().getValue().startsWith("dom-6")).count() == 1);
         
         issues = FHIRValidator.validator().validate(bodyWeight, BODY_WEIGHT_PROFILE_URL);
-        Assert.assertEquals(issues.size(), 2);
+        Assert.assertEquals(issues.size(), 3);
         Assert.assertTrue(issues.stream().filter(issue -> issue.getDetails().getText().getValue().startsWith("dom-6")).count() == 1);
         Assert.assertTrue(issues.stream().filter(issue -> issue.getDetails().getText().getValue().startsWith("vs-1")).count() == 1);
     }
diff --git a/fhir-validation/src/test/java/com/ibm/fhir/validation/test/ConstraintGeneratorTest.java b/fhir-validation/src/test/java/com/ibm/fhir/validation/test/ConstraintGeneratorTest.java
new file mode 100644
index 00000000000..5fb69649368
--- /dev/null
+++ b/fhir-validation/src/test/java/com/ibm/fhir/validation/test/ConstraintGeneratorTest.java
@@ -0,0 +1,421 @@
+/*
+ * (C) Copyright IBM Corp. 2019
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.ibm.fhir.validation.test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.antlr.v4.runtime.CharStreams;
+import org.antlr.v4.runtime.CommonTokenStream;
+import org.antlr.v4.runtime.tree.ParseTree;
+
+import com.ibm.fhir.model.path.FHIRPathBaseVisitor;
+import com.ibm.fhir.model.path.FHIRPathLexer;
+import com.ibm.fhir.model.path.FHIRPathParser;
+import com.ibm.fhir.model.path.FHIRPathParser.ExpressionContext;
+import com.ibm.fhir.model.resource.StructureDefinition;
+import com.ibm.fhir.registry.FHIRRegistry;
+import com.ibm.fhir.validation.util.ConstraintGenerator;
+
+public class ConstraintGeneratorTest {
+    public static void main(String[] args) throws Exception {
+        StructureDefinition profile = FHIRRegistry.getInstance().getResource("http://hl7.org/fhir/us/core/StructureDefinition/us-core-patient", StructureDefinition.class);
+        ConstraintGenerator generator = new ConstraintGenerator(profile);
+        List<String> list = new ArrayList<>();
+        generator.generate().stream().map(constraint -> constraint.expression()).forEach(expr -> list.add(expr));
+        for (String expr : list) {
+        	System.out.println("expr: " + expr);
+        	ExpressionContext ctx = compile(expr);
+        	ctx.accept(new PrintingVisitor());
+        	System.out.println("");
+        }
+    }
+
+    public static ExpressionContext compile(String expr) {
+        FHIRPathLexer lexer = new FHIRPathLexer(CharStreams.fromString(expr));
+        CommonTokenStream tokens = new CommonTokenStream(lexer);
+        FHIRPathParser parser = new FHIRPathParser(tokens);
+        return parser.expression();
+    }
+
+    public static class PrintingVisitor extends FHIRPathBaseVisitor<Object> {
+        int indentLevel = 0;
+
+        private String indent() {
+            StringBuilder builder = new StringBuilder();
+            for (int i = 0;i < indentLevel; i++) {
+                builder.append("    ");
+            }
+            return builder.toString();
+        }
+        
+        private void print(ParseTree ctx) {
+            System.out.println(indent() + ctx.getClass().getSimpleName() + ": " + ctx.getText() + ", childCount: " + ctx.getChildCount());
+        }
+
+        @Override
+        public Object visitIndexerExpression(FHIRPathParser.IndexerExpressionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitPolarityExpression(FHIRPathParser.PolarityExpressionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitAdditiveExpression(FHIRPathParser.AdditiveExpressionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitMultiplicativeExpression(FHIRPathParser.MultiplicativeExpressionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitUnionExpression(FHIRPathParser.UnionExpressionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitOrExpression(FHIRPathParser.OrExpressionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitAndExpression(FHIRPathParser.AndExpressionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitMembershipExpression(FHIRPathParser.MembershipExpressionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitInequalityExpression(FHIRPathParser.InequalityExpressionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitInvocationExpression(FHIRPathParser.InvocationExpressionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitEqualityExpression(FHIRPathParser.EqualityExpressionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitImpliesExpression(FHIRPathParser.ImpliesExpressionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitTermExpression(FHIRPathParser.TermExpressionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitTypeExpression(FHIRPathParser.TypeExpressionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitInvocationTerm(FHIRPathParser.InvocationTermContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitLiteralTerm(FHIRPathParser.LiteralTermContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitExternalConstantTerm(FHIRPathParser.ExternalConstantTermContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitParenthesizedTerm(FHIRPathParser.ParenthesizedTermContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitNullLiteral(FHIRPathParser.NullLiteralContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitBooleanLiteral(FHIRPathParser.BooleanLiteralContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitStringLiteral(FHIRPathParser.StringLiteralContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitNumberLiteral(FHIRPathParser.NumberLiteralContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitDateTimeLiteral(FHIRPathParser.DateTimeLiteralContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitTimeLiteral(FHIRPathParser.TimeLiteralContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitQuantityLiteral(FHIRPathParser.QuantityLiteralContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitExternalConstant(FHIRPathParser.ExternalConstantContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitMemberInvocation(FHIRPathParser.MemberInvocationContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitFunctionInvocation(FHIRPathParser.FunctionInvocationContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitThisInvocation(FHIRPathParser.ThisInvocationContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitIndexInvocation(FHIRPathParser.IndexInvocationContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+
+        @Override
+        public Object visitTotalInvocation(FHIRPathParser.TotalInvocationContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitFunction(FHIRPathParser.FunctionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitParamList(FHIRPathParser.ParamListContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitQuantity(FHIRPathParser.QuantityContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitUnit(FHIRPathParser.UnitContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitDateTimePrecision(FHIRPathParser.DateTimePrecisionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitPluralDateTimePrecision(FHIRPathParser.PluralDateTimePrecisionContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitTypeSpecifier(FHIRPathParser.TypeSpecifierContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitQualifiedIdentifier(FHIRPathParser.QualifiedIdentifierContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+
+        @Override
+        public Object visitIdentifier(FHIRPathParser.IdentifierContext ctx) {
+            print(ctx);
+            indentLevel++;
+            Object result = visitChildren(ctx);
+            indentLevel--;
+            return result;
+        }
+    }
+}
\ No newline at end of file