Fix #2187, I hope

P5/Source/Guidelines/en/TD-DocumentationElements.xml

@@ -846,7 +846,7 @@ to mark any technical term, thus:
       <p>In addition to the <gi>content</gi> element, a set of general <gi>constraintSpec</gi> elements can be
         used to express rules about the validity of an element. Like some other specification elements, they
         are identifiable (using the <att>ident</att> attribute) in order that a TEI customization may
-        override, delete or change them individually. Each <gi>constraintSpec</gi> can be expressed in any
+        override, delete, or change them individually. Each <gi>constraintSpec</gi> can be expressed in any
         notation which is found useful; the notation used must be recorded using the <att>scheme</att>
         attribute.</p>
       <p>Schematron is an ISO standard (<ref target="#ISO-19757-3">ISO/IEC 19757-3:2006</ref>) which defines a

P5/Source/Specs/constraintSpec.xml

@@ -26,20 +26,22 @@ $Id$
       <elementRef key="constraint" minOccurs="0" maxOccurs="1"/>
     </sequence>
   </content>
-  <!--
-      Following <constraintSpec> might be more clearly accomplished
-      using abstract patterns, but our build process does not
-      currently support that. For an attempt at using them, see
-      https://github.com/TEIC/TEI/tree/sydb_issue-2179_1st_via_abstract_pats,
-      which was my first attempt at doing this. —Syd, 2021-10-13
-  -->
-  <constraintSpec scheme="schematron" ident="constraint-unless-delete">
+  <constraintSpec scheme="schematron" ident="empty-based-on-mode">
+    <!-- 
+         This constraint specification is much like the
+         "child-constraint-based-on-mode" for <elementSpec>, which
+         does something something similar (in that it is based on
+         @mode), but not quite the same.
+    -->
     <constraint>
-      <sch:rule context="tei:constraintSpec[ @mode eq 'delete' ]">
-        <sch:report test="child::tei:constraint">This 'constraintSpec' element has a mode= of "delete" even though it has a child constraint. Change the mode= to "add", "change", or "replace", or remove the 'constraint' child.</sch:report>
+      <sch:rule context="tei:constraintSpec[ @mode eq 'delete']">
+        <sch:report test="child::*">This constraintSpec element has a mode= of "delete" even though it has child elements. Change the mode= to "add", "change", or "replace", or remove the child elements.</sch:report>
+      </sch:rule>
+      <sch:rule context="tei:constraintSpec[ @mode eq 'change']">
+        <sch:assert test="child::*">This constraintSpec element has a mode= of "change", but does not have any child elements. Specify child elements, or change the mode= to "delete".</sch:assert>
       </sch:rule>
       <sch:rule context="tei:constraintSpec[ @mode = ('add','replace') ]">
-        <sch:assert test="child::tei:constraint">This 'constraintSpec' element has a mode= of "<sch:value-of select="@mode"/>", but does not a 'constraint' child element. Specify a constraint or change the mode= to "delete".</sch:assert>
+        <sch:assert test="child::tei:constraint">This constraintSpec element has a mode= of "<sch:value-of select="@mode"/>", but does not have a child 'constraint' element. Use a child 'constraint' element or change the mode= to "delete" or "change".</sch:assert>
       </sch:rule>
     </constraint>
   </constraintSpec>
@@ -152,6 +154,15 @@ $Id$
       </constraintSpec>
     </egXML>
   </exemplum>
+  <remarks xml:lang="en" versionDate="2022-04-09">
+    <p>A child <gi>constraint</gi> is required when the
+    <att>mode</att> attribute has the value <val>replace</val> or
+    <val>add</val> (or is not specified, as <val>add</val> is the
+    default). No child elements are permitted when the <att>mode</att>
+    attribute has the value <val>delete</val>. At least one child
+    element is required when the <att>mode</att> attribute has the
+    value <val>change</val>.</p>
+  </remarks>
   <listRef>
     <ptr target="#TDTAG"/>
   </listRef>

P5/Source/Specs/elementSpec.xml

@@ -53,6 +53,12 @@ $Id$
     </sequence>
   </content>
   <constraintSpec scheme="schematron" ident="child-constraint-based-on-mode">
+    <!-- 
+         This constraint specification is much like the
+         "empty-based-on-mode" for <constraintSpec> itself, which does
+         something something similar (in that it is based on @mode),
+         but not quite the same.
+    -->
     <constraint>
       <sch:rule context="tei:elementSpec[ @mode eq 'delete' ]">
         <sch:report test="child::*">This elementSpec element has a mode= of "delete" even though it has child elements. Change the mode= to "add", "change", or "replace", or remove the child elements.</sch:report>

P5/Utilities/subset.xsl

@@ -34,6 +34,8 @@
     happens to end with a child element.
     2020-08-30 by Syd Bauman: Better commenting. Also just copy @xml:id
     of bibliographic entries rather than processing them.
+    2021-10-01 by Syd Bauman: Per #2187, add <constraintSpec> to list
+    for which we keep_important_stuff_with_contents.
   -->
 
   <xsl:output method="xml" indent="no"/>
@@ -43,7 +45,13 @@
 
   <!-- The important parts get copied over in their entirety: -->
   <xsl:template name="keep_important_stuff_with_contents"
-      match="teiHeader | elementSpec | macroSpec | classSpec | moduleSpec | dataSpec">
+                match="teiHeader
+                     | elementSpec
+                     | macroSpec
+                     | classSpec
+                     | moduleSpec
+                     | dataSpec
+                     | constraintSpec ">
     <xsl:text>&#x0A;</xsl:text>
     <xsl:copy-of select="." /> <!--Comments & PIs inside me are copied, too-->
   </xsl:template>