anchor.diff:      |   stringValue
       |   bitsValue
       |   objectIdentifierValue
  +    |   ipValue
       ;
   
   value
  
positive.code: 
  fragment LOWER
      : ('a'..'z')
      ;
  
  NUMBER
  
negative.code:     : CSTRING
      ;
  
  ipValue
      : IP
      ;
  
  signedNumber:
      NUMBER
      ;
  