ABORT

  Stops any executing procedures and causes TPU to wait for the next
  keypress.

  ABORT is a TPU language construct, not a built-in procedure.  ABORT has
  no parameters or completion codes.  You cannot use the EXPAND_NAME
  built-in on ABORT.

  Example

  The following error handler stops execution of any currently executing
  procedures and returns back to TPU's main loop:

     ON_ERROR
         MESSAGE ("Aborting because of error.");
         ABORT;
     ENDON_ERROR