Alt. According to the original rules, anything which is not Canon-on-Canon or Nikon-on-Nikon is alt. This is because these two combinations already have their own forums. AI or AI-S on Nikon squeaks through because this is not a popular combination over in the NoN forum, and can barely keep one thread alive.
Anyway, the feeling, the photos, the mindsets, everything is quite different between CoC and NoN people and the alt people who hang around here. Here we have people who came from CoC or NoN and felt there was something missing. They start experimenting and trying things, and have long discussions about esoteric topics which over in the mainstream fora will just get you weird looks.