Linerider,
In this context, Springbok is talking about a Cruise Relief Pilot (i.e. only qualified to relieve operating crew during cruise.). Many Airlines (e.g Qantas, Cathay) ultilise them on long haul routes, thus only ever needing one Captain and one F/O.
I take it S/O in Qatar is a rank that still entitles the holder to be Co-Pilot of the aircraft and is allowed to takeoff and land?