anchor.diff:  attr_field
   	: ID;
   		
  -boolean_literal
  -	: keyTRUE 
  -	| keyFALSE
  -	;
  -	
   string_literal
   	: QUOTED;
   	
  
positive.code: arithmetic_primary
  	: numeric_literal
  	| LPAREN simple_arithmetic_expr RPAREN
  	| functions_returning_numerics
  	//| attr_field
  	;
  
  string_expr
  
negative.code: keyOR 		: {AntlrActions.isKeyword(input, "OR")}? ID;
  keyAND 		: {AntlrActions.isKeyword(input, "AND")}? ID;
  keyNOT 		: {AntlrActions.isKeyword(input, "NOT")}? ID;
  keyBETWEEN 	: {AntlrActions.isKeyword(input, "BETWEEN")}? ID;
  keyNULL 	: {AntlrActions.isKeyword(input, "NULL")}? ID;
  keyLOWER 	: {AntlrActions.isKeyword(input, "LOWER")}? ID;
  