anchor.diff:  	additiveExpr ( "to"^ additiveExpr )?
   	;
   
  +// === Operators ===
  +	
   additiveExpr throws XPathException
   :
   	multiplicativeExpr ( ( PLUS^ | MINUS^ ) multiplicativeExpr )*
  
positive.code: 		( "intersect"^ | "except"^ ) pathExpr
  	)*
  	;
  	
  pathExpr throws XPathException
  :
  
negative.code: 	COMP_DOC_CONSTRUCTOR
  	;
  
  // === XPointer ===
  
  xpointer throws XPathException
  :
  	"xpointer"^ LPAREN! ex:expr RPAREN!
  