There are some things in the game which belie my limited understanding. For one, officer Presley in ME1 seems to have gone from seaman to officer, having skipped most or all of NCO. I was always told that if you didn't go in as an officer you weren't going to be one (granted, my friends tend towards lazy "tell me who to shoot boss" kinda soldiers). Can you go from enlisted/NCO to officer? Just gotta get a degree, pass some tests, or?
Also, do you have any idea what the other alphanumeric categorizations are? N is special forces. what about the other 25? They stand in for MOS, so it's possible to find cognates there, but have only basic understanding of the attributes. And what does special forces consist of? Seriously? I've heard from fanboys who treat SF operatives like anime fans treat ninjas, I've heard from enlisted who treat them as arrogant jerks with a slightly tougher job, as arrogant jerks with a paradise for no reason, and as arrogant jerks who got the cool missions and training. I honestly cannot find a solid, distinguishing line that I can verify.
Gonna play Mass: the Effecting and would like some, You know, actual believable military structure.