Yozz. the easy way to get round the DPM rank slides bit it to look at the cap-bADGE. If it is made of metal then it is being worn by a non-commissioned rank. If it is embriodered (like a mini-blazer badge)then it is being worn by an officer. As a rule of thumb, if the officer is more than about 5 years older than you, chances are he is a "sir". I have to admit though, the RAF WO can look like an officer from a distance in a chip-bag as the badges are almost the same (if not actually). That still would not be the case in the brown warrior master-race as WOs still wear the same cap bades as the soldiers.