The rules (at least for TNG up through about 2380) seem to be that you wear departmental colors until one of two things happens:
1. promotion to CommanderAs far as I can tell, anybody who gets promoted to the rank of Commander gets the red duty uniform regardless of department (with the exception of officers serving in Medical roles). This appears to explain Riker, Chakotay, and Sisko wearing red, while Commander Beverly Crusher still wears Medical blue. It also explains LaForge wearing red as a Captain in the provisional future of VOY: "Timeless".
2. assignment as First Officer, Executive Officer, or similar command assistance role
The use of the red Command color (regardless of department) for officers below the rank of Commander serving in Command assistance roles is a little trickier, but we saw this multiple times as well:
- Lt. Cmdr. Sisko as First Officer of the Saratoga
- Lt. Cmdr. Data as temporary First Officer of the Enterprise-D
- Lt. Cmdr. Worf as Strategic Operations Officer aboard Deep Space 9 from 2372 to 2375
So how does all this sound? Reasonable? Or are there obvious counter-examples I've missed? If so, let's hear your definition of the rules for non-Helm officers wearing red!
To get that process started, excluding officers assigned to Helm I'd be interested in hearing of examples of Lieutenant Commanders in non-Command roles wearing red, or of Ensigns, Lieutenants j.g., or Lieutenants wearing red. For example, in the "fake future" of TNG: "Future Imperfect", what color did Commander LaForge wear? (Note: I'm ignoring the colors worn by Starfleet Academy cadets, whose use of red may not be sufficiently well supported by canon to figure out.)
So based on all of this, I have two questions:
1. Will Star Trek Online automatically generate the department/rank/role color of whatever duty or dress uniform you're wearing? That might be an effective way of insuring that players know the roles of other players in a group, but it would take away some level of agency from players. So which of these goals is more important for this game?
2. Will Star Trek Online use the "serving in Command assistance role" rule to determine which Lt. Commanders wear red?
Man, with geek-mode questions like these being flung at Star Trek Online's developers, designing this game has just got to be the biggest barrel of fun ever. :)