Library /sys$common/syshlp/nclhelp.hlb set, session_control, application, network priority (OpenVMS)  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Default: 0             Value: 0-225

    When operating over Connectionless Network Service (CLNS),
    indicates network priority encoded in the NPDU (network protocol
    data unit) header for all transmitted packets.  It can be used by
    intermediate systems to assign the packets to queues of
    appropriate priority.