Library /sys$common/syshlp/tcpip$ucp_help.hlb SET, CONFIGURATION, INTERFACE, Qualifiers, /NETWORK_MASK  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /NETWORK_MASK=IP_address

    Required if you use subnets.

    The part of the host field of the IP address identified as the
    subnet.

    The software calculates the default by the following methods:

    o  Setting the bits representing the network fields to 1

    o  Setting the bits representing the host field to 0

    An IP address consists of a network number and a host number. You
    can also divide the host field into a site-specific subnetwork
    and host field.