anchor.diff:      : G O T O
       ;
   
  -HALT
  +HALT1
       : H A L T
  +    ;
  +
  +HALT2
  +    : H
       ;
   
   HANG
  
positive.code:     ;
  
  commandname
      : (BREAK | CLOSE | DO | ELSE | GOTO | HALT | HANG | IF | JOB
        | KILL | LOCK | MERGE | NEW | OPEN | READ | TCOMMIT
        | TRESTART | TROLLBACK | TSTART | USE | VIEW| XECUTE)
        | set 
        | form
        | write
        | quit
      ;
  
  arglist
  
negative.code:     : M E R G E
      ;
  
  NEW1
      : N E W
      ;
  
  NEW2
      : N
      ;
  
  OPEN
  