But first, this:
Surely it is not what it looks like?....MIL/Space is odd in not having sergeants. Or any of the lower ranks, for that matter. Instead they've got "Techs," on the notion that there is no such thing as a non-technical Space Marine. They might be right, but that means the guys (and gals) who would otherwise be Drill Instructors are instead DTs -- or HETs, Human-Engineering Techs. I would recommend one refrain from snickering, percussive maintenance being a possibility. The basic Tech skill would be "fighter." Insignia resembles older US types, with one or more symbols between rocker and chevron. (Yes, worn point down. Why? I could guess but I'll go with the semi-official answer: "Aerodynamics.") A Tech is a "general specialist" and all but a raw enlistee or one-striper has at least one area of particular skill besides battle in both shirtsleeves/planetary and vacuum/zero-G environments.
The higher ranks are (slightly) unusual as well, mostly in having a simplified rank structure and insignia and the measures taken to ensure a remarkable degree of exposure to actual combat conditions. Pogues and fobbits are, simply, not part of the system. This has its own inefficiencies, which the enterprise appears quite willing to tolerate.
