perfect T: what is it?

Plz help me understand this:
Everyone looked the same, everyone had it down to such a perfect T. You get bored. That's when you have to say, 'I will be worst-dressed.'", on her questionable choice of Oscar attire this year (from Personal quotes of Uma Thurman, from IMDb)

I don't know where it comes from, but the idiom "done to a T" means done perfectly. I'm sure it has some literal origin, but I don't know what it is.

I'm wondering if that idiom, "done to a T", comes from the phrase "to dot one i's and cross one's t's", meaning "to be precise, exact".

Uriel and Guest,
After you've made it clear what the exact expressin is, I found this:
http://www.phrases.org.uk/bulletin_board/13/messages/669.html
the origin is not clear yet, but here is a "to a tittle" expression given as an origin.

sorry for the mistake:expression