RDO as a foreign DCL command is useful in DCL command procedures
    because it lets you test the success or failure of the RDO DCL
    command line. For example, after each DCL command, you can enter
    in your procedure:

    $ IF $SEVERITY .NES. "1" THEN GOTO HANDLE_ERROR

    The integer values for each DCL severity level are:

    Value           Severity

    0               Warning
    1               Success
    2               Error
    3               Information
    4               Severe (fatal) error

    The possible integer values returned by RDO are 1, 2, or 4. The
    specific status codes returned by RDO are:

    SS$_NORMAL
    RDO-E-ERRDET, an error was detected
    RDO-F-SEVERRDET, a severe error was detected

    These are returned in DCL's $STATUS symbol.

    Users who currently invoke RDO as a foreign command will receive
    one of the above (as additional) messages if the RDO command
    fails. See the OpenVMS DCL Dictionary for more information about
    handling errors in DCL command procedures.