o  robot_info - This is the address of a robot_info_t structure
       initialized using mrd_startup(3mrd) or mrd_show(3mrd). This
       data structure contains the element starting address and
       counts for each type of element, which are needed to map an
       absolute element to the correct zero relative address and
       type.

    o  dev_status - The dev_status is the address of a dev_status_
       t structure, which is used to pass back detailed error
       information in the event of a command failure.

    o  os_status - When mrd_request_sense(3mrd) is used directly
       by an application, this argument should be MRD_CHECK_SENSE,
       or the operating system specific error code that indicates a
       device failure. On Digital UNIX this is EIO.