Hi Micha,
Thanks for your reply. One more question:

Hi JP,

tid = thread id? How is this generated since it doesn't auto increment?

This is the id of the first posting in a thread where pid == 0

So all posts in a thread share the same tid?

uniqid = ?? This is a varchar string. What does it mean? How is it generated?

I don't know.

hp =?? What is this entry for?

Homepage - shown, if the user is not registered.

Also, can someone point me to the php file that actually processes a post and enters it into the the db?

functions.inc.php, isn't it?

I could find the INSERT there. I think it's in includes/posting.inc.php but I'm not quite following the logic yet.
Regards,
JP