TPU$_EXITING       A result of EXIT (when the default condition
                       handler is established).
    TPU$_NONANSICRT    A result of operation termination - results
                       when you call DECTPU with TPU$DISPLAYFILE
                       set to nodisplay and you attempt to execute
                       screen-oriented commands.
    TPU$_QUITTING      A result of QUIT (when the default condition
                       handler is established).
    TPU$_RECOVERFAIL   A recovery operation was terminated
                       abnormally.