"Enter Phase IV prefix"

    Having chosen a Phase IV compatible address for this system,
    you may also specify a Phase IV Prefix, which together with the
    node address forms the complete network address for this system.
    All nodes within a single addressing domain contain the same IDP
    in their network addresses. The default value of "49::" is the
    "private network" IDP, which is appropriate for a Phase IV DECnet
    network that contains some DECnet-Plus systems. Please contact
    your network manager if you are in doubt as to your network's
    Phase IV Prefix value, or indeed if you are unsure how to answer
    this question at all.

    DECnet-Plus systems reference all network addresses (including
    Phase IV addresses) using OSI NSAP address formats. The Phase IV
    prefix and the Phase IV node address are used to construct the
    complete NSAP address. All DECnet-Plus systems within a single
    routing domain use this Phase IV prefix to form the Phase IV-
    compatible NSAP address. This prefix consists of the OSI address
    initial domain part (IDP) and possibly the preDSP portion of
    the domain specific part (DSP). DECnet-Plus for VMS Introduction,
    Planning, and Glossary contains more information about NSAPs.

    The default value for the prefix is the number 49::, which
    specifies that your system will be part of a private local
    network. This value is generally appropriate for networks that
    will not be interconnected with other OSI networks. If your
    network is going to be connected with other OSI networks, you
    must enter a globally unique IDP.

                                   NOTE

       If you are using an IDP other than 49::, it must be assigned
       by an authorized standards organization, such as ANSI, or
       you must construct an IDP that you know will be globally
       unique (based on your telephone number, for instance).
       DECnet-Plus for VMS Introduction, Planning, and Glossary
       contains a detailed description of how to construct an IDP
       and how to apply to a standards organization for an IDP.

    If you are in doubt about which prefix value to use, contact your
    network manager.

    Enter the Phase IV prefix you want to use.