Just another vote against Markdown. Markdown is OK for simple docs, but very poor for wiki where inter-page links are the Magic Sauce. Creole markup is a lot better for wikiing imho.
I wouldn't store the file format in the file extension; rather store metadata properly as metadata. Chances are that the application wants to hold a lot more metadata anyway, so you're going to need a metadata storage scheme anyway. (Yes, I am a lone crusader for eliminating metadata from filenames.)
I wouldn't store the file format in the file extension; rather store metadata properly as metadata. Chances are that the application wants to hold a lot more metadata anyway, so you're going to need a metadata storage scheme anyway. (Yes, I am a lone crusader for eliminating metadata from filenames.)