VMS Help Sys Parameters, QBUS_MULT_INTR  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    (VAX only) QBUS_MULT_INTR enables (1)  multilevel interrupt
    dispatching on systems that use the Q22-bus adapter. Refer to the
    OpenVMS VAX Device Support Manual for more information about the
    QBUS_MULT_INTR system parameter. (This manual has been archived
    but is available on the OpenVMS Documentation CD-ROM.)

    This special parameter is used by Compaq and is subject to
    change. Do not change this parameter unless Compaq recommends
    that you do so.