The mrd_load(3mrd) function is a specialized interface to the
    SCSI Move Medium command (or DSA equivalent). For the robot
    specified by robot_name, the routine will attempt to move the
    cartridge in the specified slot to the specified drive. Element
    addresses are zero based. On subsystems that support inverting a
    cartridge during a move, the cartridge_side argument can be used
    to indicate that the cartridge should be inverted.

    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 drive address will be verified they are within the valid of
    those elements on the robot.

    The volume_tag argument can be used to perform cartridge volume
    tag verification before the move. If the cartridge volume tag at
    the port doesn't match that specified by this argument, then mrd_
    load(3mrd) will fail with the status MRD_STATUS_CART_INVALID. If
    volume_tag 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.