Hello. I was looking at the schema that Koha uses for its database, and noticed a few peculiarities that I wonder if anyone could shed some light on: The serial table uses VARCHAR(100) for serial.biblionumber and serial.subscriptionid. Is there any context in which those are not numeric identifiers? Presumably as a result of that, there are no foreign key constraints on the serial table. I think there probably should be. There's a similar situation with the subscription table: subscription.biblionumber doesn't have a foreign key relation with biblio.biblionumber, nor, indeed, any index at all. Foreign keys are also lacking for subscription.aqbooksellerid and subscription.aqbudgetid. On the subject of foreign keys, should items.itype have a foreign key linking it to itemtypes? My understanding of foreign key relationships is that they're a Good Thing because they provide a means to ensure referential integrity. Am I missing something in these particular cases (and there are probably others, these are just the ones I happened to notice), or would people say this was probably just an oversight? Regards, Jared Camins-Esakov -- Jared Camins-Esakov Bibliographer, C & P Bibliography Services, LLC (phone) +1 (917) 727-3445 (e-mail) jcamins@cpbibliography.com (web) http://www.cpbibliography.com/