YES, it's VEST. Basically there are 8 parts to the band uniform:

1. blouse
2. vest
3. skirt
4. school badge
5. musicianship badge
6. high socks
7. garters
8. court shoes

You wear 1 beneath 3 and 2 over both of them, then put 4 at where you would normally put it on your pinafore on 2 and 5 on 1 (is it your right arm or left arm? Ö). Wear 6, put 7 just below the back of your knee, fold 6 down, then fold it up again and again and again until you see ribbons, then wear 8.

Yup, and if you have long hair you're supposed to tie it into french braids with green and black ribbons. I think.

Um and yeah you must remember to wear underwear also X) DO NOT JUST COME IN THESE 8 PIECES AND FORGET THAT! ._.

Yeppp that's all I guess. Hope it helps! :)