The International Serial Book Number was invented in 1965.

Originally it was nine digits long. Then it became ten. In 2007, it expanded to a sequence of 13.

What is this sequence of numbers? A product identifier, used by publishers, booksellers and libraries for ordering, listing and stock control purposes. Through the ISB number the book can be tracked down and, if it’s in print, or in a library, a copy can be obtained.

You can publish without an ISBN, of course. But if you want people to be able to find your book, both during its lifetime and in libraries after we’re all long gone, an ISBN is a handy thing.

Publishers buy these numbers in blocks. You can’t buy them individually. In 2005, when I began HappenStance I bought ten, which is the smallest number you could (and can) purchase at one go. They were dead cheap. I don’t recall the exact cost but I think it was less than £1.00 per number. Since then, the price has gone up.

Ten ISBNs currently cost £126.00.  One hundred cost £294.00. A thousand cost £774.00.

Anyway, I got my first ten in 2005. Quite quickly after that (a year or so later) I bought a hundred and they cost something very close to a hundred quid. One hundred! That seemed a huge number to me at the time.

I’ve just come to the end of that hundred numbers and I’ve bought another hundred. I did consider buying a thousand but . . . I’m sixty. One can only do so much in a lifetime.

There’s little poetry in a list of numbers, it seems to me. However, I found it oddly moving when I realized that the first ISBN in my last hundred was Tom Duddy’s pamphlet The Small Hours: 978-1-905939-00-8.

The last number of that same block is 978-1-905939-99-2. It belongs to Tom Duddy’s posthumous volume The Years. I’m finalising this book for print right now. More about Duddy, and much else, soon.