In Star Trek TOS you very frequently get glimpses of the female crew's panties under their short skirt uniforms.
In every case I've noticed they are always a matching color.
This makes me wonder -- were the matching panties in fact an official part of Starfleet uniform?
Also, was there any point in Star Trek TOS where a female crew member wore anything except a mini-skirt and matching panties? If not, how long was the period during which the Federation required this of its female crew (it would've been after Star Trek Enterprise and before Star Trek TNG, I think)?