anchor.diff:                  | Realtime
                   | Time
                   | Reg
  -                | String
  +                | SVString
                   | bits_type
                   | user_type
                   ;
  
positive.code:                 //| Realtime
                  //| Time
                  //| Reg
                  //| String
                  //| bits_type
                  ;
  
  
negative.code: Specify : 'specify' ;
  Specparam : 'specparam' ;
  Static : 'static' ;
  SVString : 'string' ;
  Strong0 : 'strong0' ;
  Strong1 : 'strong1' ;
  Struct : 'struct' ;
  