The following MRD_ELEMENT codes are those currently supported by
    mrd_strelement(3mrd), with their corresponding default strings.

    The first items listed are self-explanatory.

    o  MRD_ELEMENT_TRANSPORT - Transport

    o  MRD_ELEMENT_SLOT - Slot

    o  MRD_ELEMENT_PORT - Port

    o  MRD_ELEMENT_DRIVE - Drive

    o  MRD_ELEMENT_EMPTY - Empty

    o  MRD_ELEMENT_FULL - Full

    o  MRD_ELEMENT_EXCEPT - Exception

    o  MRD_ELEMENT_ACCESS - Access

    o  MRD_ELEMENT_INPORT - Inport is suitable for use when the
       ELEMENT_IMPENB bit is set in the state and data.state field
       of the element_info_t data.

    o  MRD_ELEMENT_OUTPORT - OUTPORT is suitable for use when the
       ELEMENT_EXPENB bit is set in the state and data.state field of
       the element_info_t data.

    o  MRD_ELEMENT_IOPORT - IOPORT suitable for use when the ELEMENT_
       IMPENB and ELEMENT_EXPENB bits are set in the state and
       data.state field of the element_info_t data.

    o  MRD_ELEMENT_PASS - PassThru suitable in those cases where
       the Pass-through mechanism of the TL820 can be identified.
       Currently, the only way to do this is to know the absolute
       address of the PTM depending on whether the library is in
       Multi-unit Single-LUN (Transport 1) mode or Single-unit
       Single-LUN (Port 2) mode.

    o  MRD_ELEMENT_MYSTERY - This code is suitable when neither
       the ELEMENT_IMPENB nor ELEMENT_EXPENB bits are set in the
       state and data.state field of the element_info_t data. Most
       medium-changers identify their ports, when they have one
       or the other, or both. The MRD engineering team has never
       encountered a (correctly functioning) medium-changer with a
       Mystery Port.
       * We do not expect this text to survive critical
         review of the management, but we tried.