The mrd_eject(3mrd) function is a specialized interface to the
    SCSI Move Medium command. For the robot specified by robot_name,
    the routine will attempt to move the cartridge in the specified
    slot to the specified port. Element addresses are zero based.

    The robot will be opened and the arguments to the function will
    be verified to make sure they are safe and appropriate. The slot
    and port address will be verified they are within the valid range
    of those elements on the robot.

    The cartridge_name argument can be used to perform cartridge
    volume tag verification before the move. If the cartridge volume
    tag at the slot doesn't match that specified by this argument,
    then mrd_eject(3mrd) will fail with the status MRD_STATUS_CART_
    INVALID. If cartridge_name argument is a NULL pointer, an empty
    string or used on a robot without vision support this argument is
    silently ignored and the volume tag check will not be made.

    If the slot string is an empty string and the library is a TL820
    family member, this routine will attempt to move a cartrige on
    the PTM to the port specified by the port argument. This is the
    equivalent of the Eject Port command of the CLI.