I have been confused about this, and I am not sure that there is a consensus. I used to put NonMusic if starting a nonmusical thread, but was told that the BS prefix is what means this isn't about music but I still think it's worth discussing (if not, why post, right?) - so I stopped doing it and just use BS. I do try to be explicit that it's about Mutations or something, so if you click, see the question and it isn't musical, just hit Back and go on. Am I now being a bad mudcatter?