If anyone is trying to start a thread and struggling with the XAO, here's how to do it: Start the thread while in latest posts or home and you will have the choose forum option available. Go to the bottom, enter XAO in the company code and your sentiment and postion. Then select the forum. When you choose Short Term Trading, the company code will disappear but it stays in the background as you have already selected it. (Hence the need to fill that bit in first). Then just enter your title and post and away you go.
Don't start a thread while you're in the STT forum page because that thread start button doesn't give you the option to select the forum, code, postion etc.
If you stuff it up, don't panic. No need to try again. Just use the report button and one of the friendly mods will add the XAO tag.