anchor.diff:      ;
   
   bitsType:
  -    'BITS' '{' bitsEnumeration '}'
  +    'BITS' ('{' bitsEnumeration '}')?
       ;
   
   bitsEnumeration:
  
positive.code: grammar ASN;
  
  moduleDefinition :
      IDENTIFIER
      'DEFINITIONS'
      ASSIGN_OP
      'BEGIN'
      moduleBody
      'END'
      ;
  
  moduleBody :
  
negative.code:     | name='OBJECTS' objects
      | name='VARIABLES' variables
      | name='INDEX' index
      | name='DEFVAL' '{' defValue '}'
      | name='DISPLAY-HINT' stringValue
      | name='NOTIFICATIONS' notifications
      | name='AUGMENTS' augments
  