[Koha-devel] what are biblio, biblioitems and items tables

[paul POULAIN]

I can't understand what means the 3 tables biblio biblioitems and items.
A biblio contains the datas for a book we can have, or not have in our 
library. It contains the fact that such a document EXISTS.
An item is a data to explain that we POSSESS a biblio, where, since 
when, at which costs...

But what's the hell is a biblioitem ? Where is it used ? How could be a 
definition constraint with biblio/item be writen if mySQL supported them ?

Thank's
--
Paul