Лексическая структура выражения

[28]	ExprToken	::=	'(' \| ')' \| '[' \| ']' \| '.' \| '..' \| '@' \| ',' \| '::'
			\|
			\|
			\|
			\|
			\|
			\|
			\|
			\|
[29]	Literal	::=	'"' [^"]* '"'
			\| "'" [^']* "'"
[30]	Number	::=	('.' ?)?
			\| '.'
[31]	Digits	::=	[0-9]+
[32]	Operator	::=
			\|
			\| '/' \| '//' \| '\|' \| '+' \| '-' \| '=' \| '!=' \| '<' \| '<=' \| '>' \| '>='
[33]	OperatorName	::=	'and' \| 'or' \| 'mod' \| 'div'
[34]	MultiplyOperator	::=	'*'
[35]	FunctionName	::=	-
[36]	VariableReference	::=	'$'
[37]	NameTest	::=	'*'
			\| ':' '*'
			\|
[38]	NodeType	::=	'comment'
			\| 'text'
			\| 'processing-instruction'
			\| 'node'
[39]	ExprWhitespace	::=