The mrd_inject(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
    port to the specified slot. 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 port
    and slot 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_
    inject(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.

    The TL820 family requires special handling within the mrd_
    inject(3mrd) routine, because of the way the Input/Output Device
    (IOD) works. This routine will explicitly check the specified
    inport to see if it is full. If empty and the robot is a TL820,
    the Pass-through mechanism will then be checked. If the PTM is
    full the source address will be reset to the PTM. If both are
    empty, the routine will send a Ready Inport command to enable the
    IOD. A one minute polling loop will be performed waiting for the
    inport to become full, five seconds between polls. If this first
    loop fails, the Ready Inport will be sent again and the loop
    repeated. This allows the user two minutes to put a tape into the
    inport.

    If volume tag verification is desired on the TL820, the cartridge
    will be moved to the PTM so the volume tag can be read. If the
    check fails, the cartridge will left on the PTM. If the mrd_
    inject(3mrd) is repeated with the correct volume tag or without
    one, the cartridge will be found on the PTM and the Move Medium
    command will proceed from there.