# "Number line" in books--how to know what it means? **URL:** \ **Category:** Cafe Society\ **Created:** [March 3, 2009, 5:14pm UTC](https://boards.straightdope.com/t/number-line-in-books-how-to-know-what-it-means/488163 "2009-03-03T17:14:20Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![NoCoolUserName](https://avatars.discourse-cdn.com/v4/letter/n/5fc32e/32.png) [@NoCoolUserName](https://boards.straightdope.com/u/NoCoolUserName)\ **Post date:** [March 3, 2009, 5:14pm UTC](https://boards.straightdope.com/t/number-line-in-books-how-to-know-what-it-means/488163/1 "2009-03-03T17:14:20Z")
That number line that you sometimes see with the copyright and ISBN information. Does it means something about when the book was printed? I’ve seen it quoted in some used book descriptions, so I assume it’s important, but most of them are, like, 10 9 8 7 6 or similar. Is there a document somewhere of which numbers mean what? ---
**Author:** ![tanstaafl](https://avatars.discourse-cdn.com/v4/letter/t/ba8739/32.png) [@tanstaafl](https://boards.straightdope.com/u/tanstaafl)\ **Post date:** [March 3, 2009, 5:21pm UTC](https://boards.straightdope.com/t/number-line-in-books-how-to-know-what-it-means/488163/2 "2009-03-03T17:21:33Z")
It indicates which printing of the book you are looking at. To use your example, 10 9 8 7 6 means that it is the 6th printing of the book. ---
**Author:** ![Scarlett67](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/scarlett67/32/7387_2.png) [@Scarlett67](https://boards.straightdope.com/u/Scarlett67)\ **Post date:** [March 3, 2009, 6:37pm UTC](https://boards.straightdope.com/t/number-line-in-books-how-to-know-what-it-means/488163/3 "2009-03-03T18:37:54Z")
Yup. Back at my last Real Job at a printing company, when we ran a reprint job, we would pull out the plates or films and either etch out (on plates) or opaque/tape out (on film) the appropriate number on the print code, and then send the plates or films down the line. ---
**Author:** ![Drum\_God](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drum_god/32/44_2.png) [@Drum\_God](https://boards.straightdope.com/u/Drum_God)\ **Post date:** [March 3, 2009, 6:40pm UTC](https://boards.straightdope.com/t/number-line-in-books-how-to-know-what-it-means/488163/4 "2009-03-03T18:40:32Z")
So, what is the purpose of the print line? Why not just print “Sixth printing” or whatever? ---
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [March 3, 2009, 6:45pm UTC](https://boards.straightdope.com/t/number-line-in-books-how-to-know-what-it-means/488163/5 "2009-03-03T18:45:39Z")
Faster / easier to blank out a single number than to re-typset “Nth Printing”, I’d imagine. ---
**Author:** ![Emily\_Litella](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/emily_litella/32/3370_2.png) [@Emily\_Litella](https://boards.straightdope.com/u/Emily_Litella)\ **Post date:** [March 3, 2009, 6:51pm UTC](https://boards.straightdope.com/t/number-line-in-books-how-to-know-what-it-means/488163/6 "2009-03-03T18:51:41Z")
I’m guessing this was all back before direct-to-plate and digital printing? We print from files that can be changed easily, or at least it’s easier than grinding stuff off the plates once they’re dropped. ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [March 3, 2009, 7:58pm UTC](https://boards.straightdope.com/t/number-line-in-books-how-to-know-what-it-means/488163/7 "2009-03-03T19:58:59Z")
It’s definitely from the hot type days. Changing from “Third Printing” to “Fourth Printing” would require some work on the plates. Removing the single number is a much easier job – nothing else needs to be cast. It also was useful with phototypesetting. Now that everything’s digital, it’s not necessary, but they stick with it anyway.