VMS Help DECnet-Plus, DCL Commands, SET, Set Options  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    These are the SET command options supplied by DECnet-Plus for
    OpenVMS:

    Option                Function

    HOST/MOP              Connects your terminal to a remote system
                          by way of the current host processor using
                          the MOP protocol.

    HOST/VTP              Connects your terminal to a remote system
                          by way of the current host processor using
                          the OSI Virtual Terminal protocol.

    HOST/X29              Connects your terminal to a remote system
                          by way of the current host processor using
                          the X.25 software and the CCITT X.29
                          protocols.