Analysis, part 1 - Division Colors

Whereas in TOS and TNG, the wearer's division was indicated by the color of the tunic/jacket, then with the DS9/VOY uniforms the wearer's division was indicated by the color of their jumpsuit yoke, with First Contact, the gray (well, usually gray) VOY undershirts were upgraded to what we call the DS9/NEM division shirts. 

The DS9/NEM division shirts indicated the division of the wearer. 

Berry (aka "red") was for command:

Green (yes, green - more on that later) was for medical and sciences.

Gold was for engineering: 

Gold was also for security and especially cannon fodder: 

It is worth noting that not long before the introduction of the DS9/NEM division shirts, the sciences/medical division color had begun moving from a lighter teal to more of a green. The new DS9/NEM division shirts sealed the deal and the sciences remained in that color range through Nemesis (and, interestingly, into ENT as well).

Paradoxically (in-universe, that is), this color shift was apparent on the VOY jumpsuit yokes, as well.


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