Thats a great question! I think a submission is a hold, lock, or grab that would make someone stop, give up, go unconcious, or break a bone, tear muscles or ligaments. LOL, I know my definition is quite vaugue and maybe someone can sum it up better or come up with a better definition
As for joint manipulations, I would think that a joint manipulation would be a type of submission, would it not? Anyway, just my 2 cents, but I cant wait to get others views on this.