anchor.diff:      : G O T O
       ;
   
  -HALT1
  +HALT
       : H A L T
  -    ;
  -
  -HALT2
  -    : H
       ;
   
   HANG
  
positive.code:     ;
  
  halt_
      : (HALT1 | HALT2)
      ;
  
  write_
      : (WRITE1 | WRITE2) SPACE* arglist
      ;
  
  quit_
      : (QUIT | 'Q')
      ;
  
  new_
  
negative.code:     | write_
      | quit_
      | halt_
      | hang_
      | new_
      | break_
      | do_
      | kill_
      | (CLOSE | ELSE | GOTO | IF | JOB
      | LOCK | MERGE | OPEN | READ | TCOMMIT
      | TRESTART | TROLLBACK | TSTART | USE | VIEW | XECUTE)
      ;
  
  