anchor.diff:     | srt_next_hop
      | srt_next_table
      | srt_no_readvertise
  +   | srt_no_retain
      | srt_passive
      | srt_preference
      | srt_readvertise
      | srt_reject
      | srt_resolve
  +   | srt_retain
      | srt_tag
   ;
   
  
positive.code:    RESOLVE
  ;
  
  srt_tag
  :
     TAG tag = DEC
  
negative.code:    NO_READVERTISE
  ;
  
  srt_no_retain
  :
     NO_RETAIN
  ;
  
  srt_passive
  :
     PASSIVE
  