Yeah, some do look greek, but then others just look like bent lines or geometrical symbols. The "enter key" being a strange + also strikes me as odd. If I had to guess, I'd say that they show what would happen when you press ALT for some system, given that the legends are green like the ALT key. I've never seen the ALT functions printed before, so I'm thinking these caps had to be for a specific industry or something where those symbols would get used enough to make it worth putting them on the caps? Not sure why they bothered to put green legends on the 1-0 top keys since they are the same as the black numbers there.