Uniform questions

[Cap'n Frances]

I'm working on revising a story and I keep getting stuck on little details. One of them is what to call the shirt that Trip wears under his jumpsuit. I've always thought of it as a henley. Memory Alpha calls it a mock turtleneck but that doesn't seem quite right to me.

My other uniform question is about trousers. I know there are uniform trousers but do they wear them under the jumpsuit. You wouldn't do that with a Navy or Air Force flight suit (the closest real world analogy I know of) but the Memory Alpha article seemed to imply that they were worn under the Starfleet jumpsuit.

Any clarification you can give me would be much appreciated.