Printer's key

For the mathematical concept, see Number line.

The printer's key, also known as the number line, is a line of text printed on a book's copyright page (often the verso of the title page, especially in English-language publishing) used to indicate the print run of the particular edition. The convention appears in titles published around the middle of the 20th century; it became common practice after 1970.

A copyright page with the printer's key underlined. This version of the book is the eighteenth printing.

An example follows:

1 2 3 4 5 6 7 8 9 10

This is how the printer's key may appear in the first print run of a book. In this common example numbers are removed with subsequent printings, so if "1" is seen then the book is the first printing of that edition. If it is the second printing then the "1" is removed, meaning that the lowest number seen will be "2".

Examples

Usually, the printer's key is a series of non-repeating characters (numbers or letters). However its structure or presentation is not uniform, as shown in the following examples.

The series may be in descending or ascending sequence:

10 9 8 7 6 5 4 3 2 1

1 2 3 4 5 6 7 8 9 10

a b c d e f g h i j k

In some cases, rather than follow in unidirectional sequence, the numbers may alternate from left to right:

2 4 6 8 10 9 7 5 3 1

In other cases, number lines may include a date segment consisting of two-digit consecutive-year codes:

2 3 4 5 6    73 72 71 70

This indicates a second printing (or second impression) and that it occurred in 1970. Specifically, it is the particular imprint's second impression of the edition.

When the publisher outsources the printing to a contractor, a code identifying the contracting printer may occasionally be shown:

3 4 5 6 7 8 9 10   APC   00 99 98 97 96

The hypothetical printer's key above means

• third printing
• printed in 1996
• contracted to Acme Printing Corporation.

The examples above are not exhaustive; other key configurations may be used, especially in editions published following the advent of digital printing and print on demand.

First edition vs. first printing

Bibliographers usually define a first edition as all printings from substantially the same type setting, no matter how many printings are done. Book collectors tend to define first edition as the first printing of the first edition.

Why key characters are removed rather than added

With each successive reprint, the publisher needs to instruct the printer to change the impression character. In practice, if the plates (in offset printing) have been kept, a character can be erased, but nothing can be added. In this arrangement, all the printer need do is "rub off" the last character in sequence. Changing only the outer character requires the fewest possible changes to the page of characters, which means the smallest possible charge to the publisher. In the days of letterpress printing, where each character was a metal block, all the printer had to do was to pick out the relevant block(s) from the "sheet"; the remaining stack of blocks, which had been laboriously laid out when the page was first set up, could then be inked for the reprint. In the case of a Linotype slug, the lowest character could be filed off and the slug reused. For offset printing with metal plates, the character can be erased without damaging the rest of the plate. In each case, the change is minimal.

Digital typesetting and printing

In modern computer to plate typesetting and digital printing the entire printer's key may be easily re-imaged (instead of reset by erasing or removing individual characters). This allows additional key configurations.

References

• Ahearn, Allen & Ahearn, Patricia (2011) [originally published 1991. New York: G. P. Putnam's Sons]. Collected books: the guide to identification and values (ebook) (4th ed.). Comus, Maryland: Quill & Brush Press. ISBN 978-1-8830-6014-5. Retrieved 2022-08-10 – via Google Books.

• Boutell, Henry S. (1949) [originally published 1928. London: Elkin Mathews]. Boutell, Roger (ed.). First editions of today and how to tell them (3rd revised & enlarged ed.). Berkeley & Los Angeles: University of California Press. LCCN 50000048. OCLC 1196280655 – via Internet Archive.

• Carter, John (1995) [originally published 1952. London: Rupert Hart-Davis]. ABC for book collectors. Corrections, additions and Introduction by Barker, Nicolas (7th corrected ed.). Newcastle, Delaware: Oak Knoll Press. ISBN 9781884718052 – via Internet Archive.

• Duncan, Dennis & Smyth, Adam, eds. (2019). Book parts (1st ed.). Oxford University Press. ISBN 9780192579416. Retrieved 2022-08-10 – via Google Books.

• "Identifying a book's print run". Stop Counterfeit Books. Cengage et al. [book-publisher consortium]. 2022. Archived from the original on 2022-08-03. Retrieved 2022-08-06 – via Wayback Machine.

• Levy, Michelle & Mole, Tom (2017). The Broadview introduction to book history (paperback) (1st ed.). Peterborough, Ontario: Broadview Press. ISBN 9781554810871. Retrieved 2022-08-11 – via Google Books.

• "Machine Composition Notes and Queries". The Inland Printer. Vol. 22, no. 6. Chicago. March 1899. pp. 744–746. OCLC 714712112. Retrieved 2022-08-14 – via Google Books. p. 744: [Section byline:] Conducted by an expert.

• Rennicks, Rich (17 December 2021). "Identifying first editions". The New Antiquarian [blog]. Antiquarian & Rare Books. New York: ABAA. Archived from the original on 2022-01-03. Retrieved 2022-08-11 – via Wayback Machine.

• Stedman, E. C. (March 1918). "Filing Combinations". Hints for Operators and Machinists. The Linotype Bulletin. Vol. 14, no. 7. New York: Mergenthaler Linotype Company. p. 110. OCLC 608103572. Retrieved 2023-10-08 – via Google Books.