anchor.diff:  	
   	
   choiceType
  -	:	a=CHOICE L_BRACKET choiceItemsList choiceExtensionBody? R_BRACKET
  +	:	a=CHOICE L_BRACE choiceItemsList choiceExtensionBody? R_BRACE
   	-> ^(CHOICE_TYPE[$a] choiceItemsList choiceExtensionBody?)
   	;
   	
  
positive.code: nULL:	NULL;
  
  bitStringType
  	:	a=BIT STRING (L_BRACKET (bitStringItem (COMMA bitStringItem )* )? R_BRACKET )?	-> ^(BIT_STRING_TYPE[$a] bitStringItem*)
  	;
  
  bitStringItem 
  
negative.code: 	;		
  
  valueSetAssigment
  	:	typereference type '::=' L_BRACE elementSetSpecs R_BRACE    -> ^(VAL_SET_ASSIG typereference type elementSetSpecs)
  	;		
  
  elementSetSpecs : 
  