Thanks, that seems closest to what I meant, perhaps exactly so. Could you look at the diagram I edited in after you posted your reply, and tell me if "major" is the right term for this?

That table was a lot of effort.

Yes, I believe "students of a major" is the best term.

I did the table in Emacs (Org Mode), so it didn't take that much of effort: Org Mode auto-aligns the table as you modify i, and has plenty of shortcuts to quickly add/remove/rearrange rows and columns :).

(I did some manual post-processing inside HN text box though, as Org Mode doesn't support having single cells spanning multiple columns or rows.)