Honestly, I've never paid much attention to them either. Ditto registry numbers, rank insignia, deck numbers,and all that trivia. I mean, sure, I'll try to get them right when I working on a new book, because otherwise I'll hear about it, but I'm much more interested in the stories and characters than memorizing lots of imaginary facts and figures. Nimoy had it right the first time. Star Trek is not an encyclopedia; it's a backdrop for telling engaging stories.