Let’s say that you’re faced with organising a brand new library. There are several stacks of books about the place, empty shelves, and a barcode scanner sitting ready for your itchy trigger finger. You know that, if each book in your library has a barcode, it’ll make finding it in your catalogue much easier. That’s when you notice that each book already has a barcode on the back cover – for the ISBN. The ISBN is different for each title – why not just use that?
Everyone uses International Standard Book Number (ISBN) to identify the particular edition of a title. The International ISBN Agency (or an affiliate) supplies ISBNs to publishers. So why not use the ISBN to identify that book in your library? After all, no other titles will have the same number, will they?
The answer becomes apparent when you consider that you might have more than one copy of a book. If not now, then you could in the future. If you have one, two or thirty copies of a title in your library, the ISBN will be the same on every single one. The trouble is that the ISBN is not unique across all your copies.
To keep track of stock in your library you need a unique number or identifier for every copy or copy item in your library. This is sometimes called an “accession number” or an “item barcode”.
For example, if you used the ISBN as the copy identifier, and both copies are on loan, when one is overdue, which borrower do you contact? If a copy is returned to the library, which one is it? How do you check the history of a copy, or track it down?
Even if you’re sure that you’ll never buy another copy of a given book, you might lose the one that you have – a borrower might disappear with it or spill coffee all over it, or it might just get worn out. If you’re uniquely identifying each copy in your catalogue, you can mark the old copy as having been lost, and add a new one with a different number.
When every copy or thing in your library has its own number, you can track, trace and audit every single item. That’s why librarians will assign a unique number to every copy or item in the collection. This could be a unique number that you write it the book or it could be a barcode label representing a unique number.
You can purchase pre-printed library barcode labels as sheets or rolls. You simply peel off a barcode number and place it on the item, usually just inside the front cover.
Enter this number in the field for the accession number / item barcode / unique identifier. You can still store the ISBN number in the ISBN field on the main catalogue record which describes the title.
While it might seem easy to use the ISBN as the ‘barcode’ when cataloguing your collection, it’ll inevitably create unnecessary work down the line, so it is not good practice. The ISBN is great for finding bibliographic information, but it is not helpful as a unique barcode for a copy of a book in your library. Use unique numbers from the start, and you’ll steer clear of any number clashes in the future. And it will be easy to track all your copies.