Leadbottom: You seem to be treating folk as a genre, which it is not, no more than classical and popular can be considered genres. It is better to consider them as categories of genres.

Oh dear. The prefix is "sub." It's music because it's not literature and it's all Liberal Arts. If the subject is music industry charts & revivals... Classical is Popular because it's not R&B or Country.

Your problem is you're lacking a real world application and the proper ethics that come with. Say as you do. Do as you say. You could call them Tom, Dick, Harry & Rudolph if you please. It wouldn't matter one iota. You're not actually sorting anything at all.