VMS Help DECTPU, TPU$EXECUTE_COMMAND, Condition Values Returned  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    TPU$_SUCCESS       Normal successful completion.
    TPU$_EXECUTEFAIL   Execution aborted. This could be because of
                       execution errors or compilation errors.
    TPU$_EXITING       EXIT built-in procedure was invoked.
    TPU$_QUITTING      QUIT built-in procedure was invoked.