Description

   Given a robot_info_t structure and absolute element address,
   this routine figures out the corresponding element type and zero
   relative address. The relative address is formatted into the
   space provided by result and the element type is returned.

   A valid robot_info_t structure can be obtained by using mrd_
   startup(3mrd) or mrd_show(3mrd) to open the robot and fill in the
   robot_info_t structure.

   The SCSI-2 specification allows an absolute address of zero (0)
   to refer to a default transport, when a medium-changer has more
   than one. When handed zero as the absolute address, this routine
   will reflect this convention even if the particular medium-
   changer doesn't.