This routine performs a SCSI Move Medium command, or equivalent
    if some other I/O architecture is supported. It is used by mrd_
    move(3mrd), mrd_load(3mrd), mrd_unload(3mrd), mrd_inject(3mrd)
    and mrd_eject(3mrd). Since it accepts a robot_info_t structure
    associated with an open medium changer it can be used to perform
    multiple move commands, without having to re-open the medium
    changer as the other functions that use it do.

    The robot_info argument is the address of a robot_info_t that
    has been opened by mrd_startup(3mrd). If the medium changer isn't
    opened, the Move Medium command will fail with the operating
    system error for trying to use an unopened device. On SCSI medium
    changers, it maps directly to the SCSI Move Medium command.

    The transport address is the absolute address of the transport
    element to be used for the command. Many medium changers allow
    the use of address zero (0) as the default transport, but some
    may require a transport address that is valid for the medium
    changer. For single transport medium changers, the transport
    base address in the robot_info_t structure, transport_start is a
    suitable address.

    The source and destination addresses are absolute addresses to
    be used as the source and destination for the move. The absolute
    address can be calculated from a zero relative address by adding
    it to the base address for the element type. The routine makes
    no checks for the validity of the address, relying on the medium
    changer to do this.

    A invert value of one (1) can be used on medium changers that
    support inverting the media, when this is desired; an optical
    drive with two sided media. Otherwise a value of zero should be
    used.

    This routine uses the dev_status_t structure for handing errors.
    The dev_status_t structure includes the code, os_status, and SCSI
    error fields. The following describes how to decode errors with
    the dev_status_t structure.

    SCSI Errors

    SCSI errors are indicated when the value of the valid field of
    the SCSI error is not equal to 0. The key, asc, and ascq fields
    provide additional information to help determine the cause of the
    error.

    The code usually maps the Additional Sense Code and Additional
    Sense Code Qualifier (ASC/ASCQ) values to an MRD error. The asc
    and ascq values are copied from the request sense data returned
    by the target.

    The Additional Sense Code (asc) indicates further information
    related to the error or exception condition reported in the sense
    key field. The Additional Sense Code Qualifier (ascq) indicates
    detailed information related to the additional sense code. For
    more information, consult the SCSI-2 Specification.

    Operating System Errors

    Operating system errors are indicated when the value of the valid
    field of the SCSI error is equal to 0 and the value of the os_
    status field is not equal to 0. This result is most likely caused
    by an operating system error, and probably has a mapped error in
    MRD.

    MRD Errors

    MRD errors are indicated when the value of the os_status field is
    0, and the value of the valid field of the SCSI error is 0. This
    result is most likely caused when MRD encounters its own failure.