Hello, I have a player whose original career was a thug. She's interested in becoming an assassin. I'm a little confused by the keywords here, I understand how to figure out the experience cost. My confusion is the assassin is an "advanced" career, I know this means that it can't possibly be taken at character generation (only basic careers can), but I'm not sure if it means anything beyond that. My confusion mainly comes from the fact that there are other careers that are not basic, but are "intermediate". Most non-basic careers list specific requirements to get into them, the assassin does not.
In short, does the advanced/intermediate mean anything beyond you can't pick them at the start (do you have to go basic, intermediate, advanced; or be a specific rank to take an intermediate/advanced)? If so or if there are any rules about these at all, could you point me in the direction and to which book they're in.