diff --git a/xpath-grammar.txt b/xpath-grammar.txt
new file mode 100644
index 00000000..3f269e5c
--- /dev/null
+++ b/xpath-grammar.txt
@@ -0,0 +1,138 @@
+[1]     LocationPath                    ::= RelativeLocationPath
+                                          | AbsoluteLocationPath
+
+[2]     AbsoluteLocationPath            ::= '/' RelativeLocationPath?
+                                          | AbbreviatedAbsoluteLocationPath
+
+[3]     RelativeLocationPath            ::= Step
+                                          | RelativeLocationPath '/' Step
+                                          | AbbreviatedRelativeLocationPath
+
+[4]     Step                            ::= AxisSpecifier NodeTest Predicate*
+                                          | AbbreviatedStep
+
+[5]     AxisSpecifier                   ::= AxisName '::'
+                                          | AbbreviatedAxisSpecifier
+
+[6]     AxisName                        ::= 'ancestor'
+                                          | 'ancestor-or-self'
+                                          | 'attribute'
+                                          | 'child'
+                                          | 'descendant'
+                                          | 'descendant-or-self'
+                                          | 'following'
+                                          | 'following-sibling'
+                                          | 'namespace'
+                                          | 'parent'
+                                          | 'preceding'
+                                          | 'preceding-sibling'
+                                          | 'self'
+
+[7]     NodeTest                        ::= NameTest
+                                          | NodeType '(' ')'
+                                          | 'processing-instruction' '(' Literal ')'
+
+[8]     Predicate                       ::= '[' PredicateExpr ']'
+
+[9]     PredicateExpr                   ::= Expr
+
+[10]    AbbreviatedAbsoluteLocationPath ::= '//' RelativeLocationPath
+
+[11]    AbbreviatedRelativeLocationPath ::= RelativeLocationPath '//' Step
+
+[12]    AbbreviatedStep                 ::= '.'
+                                          | '..'
+
+[13]    AbbreviatedAxisSpecifier        ::= '@'?
+
+[14]    Expr                            ::= OrExpr
+
+[15]    PrimaryExpr                     ::= VariableReference
+                                          | '(' Expr ')'
+                                          | Literal
+                                          | Number
+                                          | FunctionCall
+
+[16]    FunctionCall                    ::= FunctionName '(' ( Argument ( ',' Argument )* )? ')'
+
+[17]    Argument                        ::= Expr
+
+[18]    UnionExpr                       ::= PathExpr
+                                          | UnionExpr '|' PathExpr
+
+[19]    PathExpr                        ::= LocationPath
+                                          | FilterExpr
+                                          | FilterExpr '/' RelativeLocationPath
+                                          | FilterExpr '//' RelativeLocationPath
+
+[20]    FilterExpr                      ::= PrimaryExpr
+                                          | FilterExpr Predicate
+
+[21]    OrExpr                          ::= AndExpr
+                                          | OrExpr 'or' AndExpr
+
+[22]    AndExpr                         ::= EqualityExpr
+                                          | AndExpr 'and' EqualityExpr
+
+[23]    EqualityExpr                    ::= RelationalExpr
+                                          | EqualityExpr '=' RelationalExpr
+                                          | EqualityExpr '!=' RelationalExpr
+
+[24]    RelationalExpr                  ::= AdditiveExpr
+                                          | RelationalExpr '<' AdditiveExpr
+                                          | RelationalExpr '>' AdditiveExpr
+                                          | RelationalExpr '<=' AdditiveExpr
+                                          | RelationalExpr '>=' AdditiveExpr
+
+[25]    AdditiveExpr                    ::= MultiplicativeExpr
+                                          | AdditiveExpr '+' MultiplicativeExpr
+                                          | AdditiveExpr '-' MultiplicativeExpr
+
+[26]    MultiplicativeExpr              ::= UnaryExpr
+                                          | MultiplicativeExpr MultiplyOperator UnaryExpr
+                                          | MultiplicativeExpr 'div' UnaryExpr
+                                          | MultiplicativeExpr 'mod' UnaryExpr
+
+[27]    UnaryExpr                       ::= UnionExpr
+                                          | '-' UnaryExpr
+
+[28]    ExprToken                       ::= '(' | ')' | '[' | ']' | '.' | '..' | '@' | ',' | '::'
+                                          | NameTest
+                                          | NodeType
+                                          | Operator
+                                          | FunctionName
+                                          | AxisName
+                                          | Literal
+                                          | Number
+                                          | VariableReference
+
+[29]    Literal                         ::= '"' [^"]* '"'
+                                          | "'" [^']* "'"
+
+[30]    Number                          ::= Digits ('.' Digits?)?
+                                          | '.' Digits
+
+[31]    Digits                          ::= [0-9]+
+
+[32]    Operator                        ::= OperatorName
+                                          | MultiplyOperator
+                                          | '/' | '//' | '|' | '+' | '-' | '=' | '!=' | '<' | '<=' | '>' | '>='
+
+[33]    OperatorName                    ::= 'and' | 'or' | 'mod' | 'div'
+
+[34]    MultiplyOperator                ::= '*'
+
+[35]    FunctionName                    ::= QName - NodeType
+
+[36]    VariableReference               ::= '$' QName
+
+[37]    NameTest                        ::= '*'
+                                          | NCName ':' '*'
+                                          | QName
+
+[38]    NodeType                        ::= 'comment'
+                                          | 'text'
+                                          | 'processing-instruction'
+                                          | 'node'
+
+[39]    ExprWhitespace                  ::= S