"978-0-230-52906-9 reporting for duty, Sir!"

Yep. That's the ISBN-13 for Shock and Awe.

Haven't you always wanted to understand how those worked? No? Neither have I. Nonetheless, I'm behind on two important projects, so this seems like a good time to find out.

Some of this is a little fuzzy to me, so if any pros want to jump in and correct me, please do.

ISBN was started as a UK-only operation by the booksellers WH Smith. It was then adopted for international use by the ISO (International Standards Organization). It jumped from 10 digits to 13 digits on January 1 of this year. The big goal in moving to 13 digits is to bring it into harmony with the overall Universal Product Code system. (I know we've all been worried about this issue.)

The first grouping of digits--the GS1 code--in the UPC system tells you what country manufactured the item. Usually. For example, Bulgarian products begin with 380; Azerbaijani products begin with 476.

But books are handled differently. Books all begin with 978. Even if they're Bulgarian. So, if you're confused as to whether you have a book in your hands or, say, a garden rake, check the first numbers of the UPC. If the first three digits are 978, it's a book. If they are 380, it's probably a garden rake, but whatever it is, it isn't a book and it definitely comes from Bulgaria.

(Just to confuse matters, sheet music used to be 979, but now some books are 979, too. I'm not sure why. So, if the first three digits are 979, try humming the contents. If you can't, it's probably a book.)

So, we have 978-0. The "0" is a language group identifier; 0 or 1 is English (why they need two numbers is a mystery. Perhaps "1" is English as a Second Language? Maybe Irvine Welsh gets his own number?) French is 2, German is 3...

Which is fine, except there are more than nine languages in the world, and English already used up 2 slots. Well, as it turns out, they allow up to five digits in this position, so it can specify up to 100,000 language groups since "0" is counted (well, actually 99,999 since English is squatting on two slots). Now it seems to me that we are actually talking about ISBN-17 here, and that they've made a hash of the whole thing, but as I said before, I'm not clear on some of this.

Okay. 978-0. A book, and in English. Now, 230. Turns out 230 is the publisher code--apparently Macmillan New Writing. Looking through other books shows 330 as the number on most Pan books, 405 on Macmillan, 333 on Macmillan Children's. But, once again, we arrive at something that doesn't quite add up. They claim that are almost 700,000 publisher codes assigned worldwide. (They also mention that a publisher can have more than one code.) Looks to me like that would take six digits, not three...Hmm. So is this actually ISBN-23?

We've got 978-0-230 explained. Sort of. 52906, I'm happy to say, appears to be the item number. I have no idea how this is assigned, but I can tell you the numbers for the first 6 MNW books are 00000 (North), 00009 (The Manuscript), 00010 (Dark Rain), 00050 (Across the Mystic Shore), 00137 (Taking Comfort), and 00185 (Selfish Jean). They continue to begin with zeros up until Eliza Graham did something peculiar that altered the fabric of the universe and Playing with the Moon vaulted up to 52887. (Though Pandora's Sisters, published later than Eliza's book, is 01828.)

We seem stuck in the 50,000s now, thanks to Eliza. In August, The Great North Road (52889), then Shock and Awe (52906, remember that number!), then The Herring Seller's Apprentice (52965), and finally Cover the Mirrors (52966). So, it's going up, but darned if I understand this system

That last little number (9, in the case of my book) is a really odd check-sum to see if the ISBN number makes sense. Here's how it works. There is a multiplier for the first 12 numbers--either 1 or 3. The multiplier alternates 1, 3, 1, 3, 1, 3... You multiply this times the ISBN number and sum it up. Like this:

9 x 1 + 7 x 3 + 8 x 1 + 0 x 3 + 2 x 1 + 3 x 3 + 0 x 1 + 5 x 3 + 2 x 1 + 9 x 3 + 0 x 1 + 6 x 3

= 9 + 21 + 8 + 0 + 2 + 9 + 0 + 15 + 2 + 27 + 0 + 18

= 111

Now you take the result, 111, and find the number you need to add to it to round up to the next multiple of ten. In this case, the next multiple of 10 is 120, and 120 - 111 = 9, so the number is 9--the same number as that last little digit in 978-0-230-52906-9.

What's the point of that, you ask? Well, I can now tell you, with certainty, that the card you are holding in your hand is the Jack of Clubs. Right?