o  data link error

    An error was reported by the Data Link layer on the load command.

 o  unrecognized client

    There is no client with the specified identification.

 o  unrecognized circuit

    There is no circuit with the specified identification.

 o  required argument omitted

    The Address and System Image arguments are required for LAN
    circuits.  If they are not present in the command line, then
    the MOP Client database entry must provide that information.
    Circuit information must also be provided on the command
    line or it must be obtainable from the specified MOP Client
    entry.

 o  entity class not supported (OpenVMS)

    MOP is not registered with EMAA.  The NET$MOP process is
    probably not started.  For instructions on how to restart
    the MOP process, refer to HELP NETWORK_MANAGEMENT MOP.