This is towards the beginning. All you ladies will get to permanently throw out your web belts. Dudes, you gotta keep it for your Dress Blue Charlies and Service Uniforms.
The levels of Marine Corps Martial Arts are
Tan
Gray
Green
Brown
Black
Because I'm paranoid I'm giving out confidential information, you can google most of this stuff. Whew. Anyway, if you are one of the cool kids who already has a Tan belt, whether you were prior service or from a previous company, you will most likely have the option to belt up, since there will be a decent amount of you. I've seen gray belts belt up to green. I think it's due to instructor availability and amount of people that already have higher belts.
MCMAP isn't graded, but you need a tan belt to graduate.