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

    TPU$_SUCCESS       Normal successful completion.
    TPU$_UNKFACILITY   The facility_index passed to this routine
                       does not match any facility index passed to
                       TPU$SPECIFY_ASYNC_ACTION.