anchor.diff:  
   itemType throws XPathException
   :
  -	( "item" LPAREN ) => "item"^ LPAREN! RPAREN! | ( . LPAREN ) => kindTest | atomicType
  +	( "empty" LPAREN ) => "empty"^ LPAREN! RPAREN! | ( . LPAREN ) => kindTest | atomicType // deprecated
  +	// conformant: ( "empty-sequence" LPAREN ) => "empty-sequence"^ LPAREN! RPAREN! | ( . LPAREN ) => kindTest | atomicType
   	;
   
   singleType throws XPathException
  
positive.code: 	additiveExpr ( "to"^ additiveExpr )?
  	;
  
  additiveExpr throws XPathException
  :
  	multiplicativeExpr ( ( PLUS^ | MINUS^ ) multiplicativeExpr )*
  
negative.code: 	{ #atomicType= #[ATOMIC_TYPE, name]; }
  	;
  
  // === Expressions ===
  	
  queryBody throws XPathException: expr ;
  
  expr throws XPathException
  