Sorry for the double post. I do have another question: What code would I use to allow my users to choose a thread prefix? Maybe something like this? (The prefix IDs For_Sale and For_Trade are already built into my forum.)
Code:
if (stristr($qo['4'], "Sale")) {
$prefixid = For_Sale;
}
elseif (stristr($qo['4'], "Trade")) {
$prefixid = For_Trade;
}
Edit: Again, never mind. Found
this post, and it works -- now my users can choose their thread prefix.