The mrd_show(3mrd) function can be used to obtain information
    about specific element types of a supported Medium-Changer.
    Medium-Changer element types that mrd_show(3mrd) can retrieve
    information about include PORT, DRIVE, SLOT and TRANSPORT. If
    a element_type of ROBOT is specified, the mrd_show(3mrd) is
    equivalent to calling mrd_startup(3mrd) - that is, robot_info
    is filled in.

    The robot_info_t data structure is described in mrd_
    startup(3mrd).

    The element_name parameter specifies the first element of the
    type element_type about which to obtain information. The element_
    count parameter specifies the number of elements of type element_
    type about which information is to be obtained.

1  –  Element Info

    The element_info_t data structure is defined in the include file
    <mrd_common.h>. The fields of this data structure are described
    below:

    o  name - The name field holds the volume tag of the media if
       applicable.

    o  state - The state field can have one of the following values:

          ELEMENT_FULL,
          ELELMENT_EMPTY, or
          ELEMENT_EXCEPT.

    o  port_type - If the element_type parameter specifies PORT, the
       port_type field will have one of the following values:

          IN_OUT_PORT,
          INPORT,
          OUTPORT.

    o  status - The status field can have one of the following
       values:

          MRD_STATUS_SLOT_INVALID,
          MRD_STATUS_DEVICE_INVALID,
          MRD_STATUS_TRANSPORT_INVALID,
          MRD_STATUS_PORT_INVALID, or
          MRD_STATUS_SUCCESS.

    o  flags - Use the ELEMENT_VALID mask on the flags field to
       indicate whether or not the full Read Element Status data
       is valid. The ELEMENT_PVOLTAG and ELEMENT_AVOLTAG indicate
       whether the primary or alternate volume tags of the Read
       Element Status data are valid.

    o  element_addr - This is the address of the element, unadjusted
       for the starting address. The routine mrd_map_element(3mrd)
       can be used to convert an absolute element address to a
       relative address and type. This field will be set to -1 when
       the information is not valid.

    o  source_addr - On most SCSI-2 medium-changers, this is the
       address where a cartridge resided before being moved to its
       current location. The routine mrd_map_element(3mrd) can be
       used to convert an absolute element address to a relative
       address and type. This field will be set to -1 when the
       information is not valid. On some SCSI-2 medium-changers (the
       DLT family loaders) this will be the element address of the
       slot itself.

    o  data - This a copy of the SCSI-2 Read Element Status data
       when the ELEMENT_VALID bit is set in the flags field. A byte-
       order neutral declaration of this data structure is included
       in the <mrd_common.h> include file as the mrd_reades_t data
       structure.