Ha ha..... a bit like a jock staffy we had on an exchange down with the yanks at Spengdahlen. He nearly gave one of the yank 'Gunny' like instructors a heart attack during a cigarette break when he asked "Where can I put my fag butt?" Poor bugger nearly broke his jaw on the floor
J = Joint - a tri=service Staff appt
G = General - an Army staff appt
N = Naval - a Navy staff appt (no kidding)
A = Air -an RAF staff appt
You will also see CJ for Combined Joint, or lots of different peoples' purple organisations all ganging up together. This is not the same as CJMN - which is lots of other countries' purples organisations all joining up. Still with me...
I have amended Murielson's excellent post with the latest thinking from Puzzle Palace - and yes, it is to 'harmonise operational capability'. Or something.