When MRU executes commands, it examines the commands for the
    presence of parameters.  If you do not specify parameters to the
    keywords slot, drive, or port, MRU supplies defaults, usually
    assuming a value of 0.

    slot_number:    An integer value indicating a physical slot in
                    the media robot.

    drv_number:     An integer value indicating a physical drive in
                    the media robot.

    port_number:    An integer value indicating a physical port in
                    the media robot.

    robot_name:     The name for the media robot.

    cartridge_name: The name of the cartridge as identified by its
                    external label.

    In the MRU system, drive, slot, and port numbering begins with 0.
    The default value for DRIVE, PORT, and SLOT is 0.