If you're looking for, or at, guestbook scripts it may be worth you peering at nms which is a well-coded set of drop-in-replacements for the less-than-secure Matt's Script Archive scripts, as started and led by davorg.

If nothing else the fact that they're commented may help you with things such as this. I would look long and hard at these before deciding I could do better myself though, they are very nice.