anchor.diff:  callStatement :
   	CALL (identifier | literal)
   	(
  -		USING (callByReferenceStatement | callByContentStatement)+
  +		USING (callByReferenceStatement | callByValueStatement | callByContentStatement)+
   	)?
   	(ON? OVERFLOW statements)?
   	onExceptionClause?
  
positive.code: 
  callByReferenceStatement :
  	(BY? REFERENCE)? (identifier | ADDRESS OF identifier | fileName)+ 
  ;
  
  callByContentStatement :
  
negative.code: ;
  
  programName :
  	cobolWord | NONNUMERICLITERAL
  ;
  
  qualifiedDataName :
  