Is there a way to see exactly what bbcodes the forum supports and what they mean? Also, I’d like to request the ability to make horizontal rules and to center text.

When you get the new version of XOOPS online, those are some things to put on the todo list (near the bottom ;-)).

AFAIK, Xoops uses standard BBCodes: http://en.wikipedia.org/wiki/Bbcode.

I have no influence in what codes are supported without hacking around, which I don’t want to do anymore on the new version (or at least as few hacks as possible) for easy updating. Maybe you’re lucky and they extended their codes. 😉

There’s said to be new editors in the package, will be interesting to see what they offer.

I hope the new one has something like FUDcode or YaBBC, because superscript, subscript, lists, and spoiler tags are handy, too. Plus, notice that YaBBC has support for embedding Flash and other plugin-based multimedia 😎