> Unfortunately — and Shel was well aware of this very quickly, but of course by that time, it was too late — ISBNs are terribly abused in the United States. The company that issues ISBNs, Bowker, charges a lot of money for ISBNs (from the perspective of small publishers, anyway), and publishers don’t necessarily read all the rules. Small publishers were re-using ISBNs, and they also took their range of ISBNs and numbered through the entire range, rather than respecting the rule that the final character is actually a checksum, and you can only iterate through some of the digits. (It’s actually worse than just not using the last digit, but I’m not getting into that here.)

If there's a single company issuing them how are there companies using ones with invalid checksums?

Here’s some ASIN trivia from my time at Amazon in the early 10’s. At least at that time, there was exactly one inventory item at Amazon that could change ASINs during its lifetime: Amazon Fresh used different ASINs for green bananas and yellow bananas.
Years ago I spent a lot of time trying to figure out how to get a Kindle to "Whispersync" sideloaded books. Eventually I figured out it was as simple as having an ASIN included in the books metadata (Calibre does this automatically now, but it was fun figuring it out manually with Python scripts).

Originally I thought the ASIN had to be valid, but eventually realized it didn't even matter, just had to match the pattern.

Some products come from AFN/FBA with an ASIN-formatted number on a barcode on the product bag, but which starts with "X" instead of "B". I believe this to be some kind of inventory tracking code that relates the product to the vendor who shipped it into the Amazon fulfillment network. At the rate of 100B ASINs allocated per year, Rebecca may be disappointed to know that in only 967 years, Amazon will begin to collide between ASINs and whatever these numbers are.

Honestly I expect they'll hit some big problems when they first allocate ASINs beyond Bxxxxxxxx as I'm sure a lot of software has begun to expect all ASINs to either be an ISBN or start with "B".

I bet there are some interesting stories from the groups that tried to use the A-prefixed ASINs.
> It’s actually worse than just not using the last digit, but I’m not getting into that here.

Clearly, using only nine characters would have been asinine.

In addition to the other associations of the name "ASIN", there was also the Pet Shop Boys hit pop song "It's A Sin", several years earlier:

> I objected to subdividing and having different parts of the string mean different things because it would substantially reduce the addressable space, and limit the number of items that could be moved through Amazon before having to go back and do this re-keying exercise again, with an even bigger code base. The people who wanted “special” ASINs were pretty persistent, though, so I threw them a bone: they could have all the ASINs that started with the letter A, and I would start the counter for ASINs at B000000000. Finally, this proposal had to get past...
TCIN - Item Number


This is to differentiate it from their in store operations: DPCI - DePartment Class Item


The problem with ASINs is that they are not unique within amazon marketplaces. So B0000001 could be a toy in USA and a Book in Germany.
I always wondered why ASINs start with B.....

Anyone know what the A.... ASINs that were mentioned in the article are/were used for?

wow this blog might be a gold mine for me rn? (also i feel like an idiot for trying to make another bookstore ecommerce platform (wip))