Stephen, Thanks for answering.

I'd recommend you put your call number in biblioitems.classification and not mess with dewey (everything should still work OK). Use some sort of unique numbering system for barcode. -- SH

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I've created an alphanumeric local call number unique to each item (copy of a title) I'm also using this as a barcode number. the first

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I plan to put this local call number into Koha's barcode field in

My numbering system is indeed unique, but is unique for every item/copy of a title, not for each biblioitem (see my original message for the scheme's details). And that number also functions as the barcode, which is why I thought that would be a good field. Are you saying it's necessary to use a biblioitem field for searching/OPAC display purposes? I can see that would make sense, but if 2.2 is going to use itemcallnumber, maybe I can use barcode in the meantime? If not, I suppose I could put the first five parts of the number - unique to each biblioitem - in the field you suggest, and then put the whole call number in the barcode field of the related items. I'd just have to remember to change both levels if the number has to change. And I still need to know if it's OK to ignore the Koha call number - it might have Dewey in it or it might be empty for a lot of records - is that OK? Thanks, Hans part of the number shows the level, then the set, then the titles, and then the individual copies. So Q010A04 means "the fourth copy of title A in set 010 at reading difficulty level Q". the items table, and link that field to MARC 852c - please confirm I got at least that right, or should I use a 9xx?