Gives access to DCL from inside RDO.

    The dollar sign ($) instructs RDO to spawn a subprocess and
    pass the next keyword to DCL for processing. You must follow the
    dollar sign with a DCL command. After DCL processes the command,
    it logs out of the subprocess and returns control to RDO.

    Example:

    RDO> $ MAIL

    MAIL>

    Format

    $ dcl-command