anchor.diff:      ;
   
   bitsType:
  -    'BITS' '{' bitsEnumeration '}'
  +    'BITS' ('{' bitsEnumeration '}')?
       ;
   
   bitsEnumeration:
  
positive.code:     |   objectIdentifierValue
      |   booleanValue
      |   stringValue
      ;
  
  referenceValue
  
negative.code: grammar ASN;
  
  moduleDefinition :
      IDENTIFIER ( '{' modulePath? '}' )?
      'DEFINITIONS'
      ASSIGN_OP
      'BEGIN'
      moduleBody
      'END'
      ;
  
  modulePath :
      (IDENTIFIER ('(' NUMBER ')')? NUMBER? )+
      ;
  
  moduleBody :
  