/sys$common/syshlp/helplib.hlb SPAWN, Qualifiers, /NOTIFY  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /NOTIFY
       /NONOTIFY (default)

    Controls whether a message is broadcast to your terminal
    notifying you that your subprocess has completed or aborted.
    This qualifier should not be used unless you specify the /NOWAIT
    qualifier. The /NOTIFY qualifier cannot be specified when the
    SPAWN command is executed from within a noninteractive process.

    Note that messages broadcast as a result of using the /NOTIFY
    qualifier are considered to be DCL messages. Therefore, if SET
    BROADCAST=NODCL is in effect, all such notification messages are
    suppressed.