Class Identifiers

Hey /prog/,
If you were to program a BBS similiar to this and wanted to make it object-oriented how would you call the classes? I guess "Reply" would do for any post after the first post. Since you often call the first poster OP (Original Poster) would you call the first post "OriginalPost"? Some suggestions would be great since I'm really bad at making decisions.

The advantage /prog/ has over newsgroups such as comp.lang.lisp is that we generally acknowledge we're full of shit, and that's part of the fun of it. The advantage newsgroups have is the people trying not to act like they're all full of shit can occasionally be helpful.