Cathy,

>Is there a published list of acceptable (and unacceptable) tags to be used in UT messages and signatures -- and how would I get this list?

I have not seen a list, but I may have missed it. You might be able to provoke such a list by trying an assortment of tags until you find one that breaks something, like the "< textarea >" tag that someone had here just a few days ago. :-)

You can test things, BTW, by sending private messages to yourself. That way you won't destroy entire thread displays like some of us have done in the past.