Of course we all know that the colored stripes on the shoulders of all ENT uniforms are intended to be a tribute to the TOS uniform colors.
Assuming this is the case: why, in ENT, is there no red?
There's the greenish/gold of command, and science blue, both the same colors as used in TOS. However, in ENT, engineers and tactical officers have PURPLE stripes on their uniforms (as can clearly be seen with Trip and Malcolm), not red. Why did they do that?