This check system – similar to the UPC check digit formula – does not catch all errors of adjacent digit transposition. Specifically, if the difference between two adjacent digits is 5, the check digit will not catch their transposition. For instance, the above example allows this situation with the 6 followed by a 1. The correct order contributes 3×6+1×1 = 19 to the sum; while, if the digits are transposed (1 followed by a 6), the contribution of those two digits will be 3×1+1×6 = 9. However, 19 and 9 are congruent modulo 10, and so produce the same, final result: both ISBNs will have a check digit of 7. The ISBN-10 formula uses the prime modulus 11 which avoids this blind spot, but requires more than the digits 0–9 to express the check digit.
Additionally, if the sum of the 2nd, 4th, 6th, 8th, 10th, and 12th digits is tripled then added to the remaining digits (1st, 3rd, 5th, 7th, 9th, 11th, and 13th), the total will always be divisible by 10 (i.e., end in 0).
ISBN-10 to ISBN-13 conversion
An ISBN-10 is converted to ISBN-13 by prepending "978" to the ISBN-10 and recalculating the final checksum digit using the ISBN-13 algorithm. The reverse process can also be performed, but not for numbers commencing with a prefix other than 978, which have no 10-digit equivalent.
Errors in usage
Publishers and libraries have varied policies about the use of the ISBN check digit. Publishers sometimes fail to check the correspondence of a book title and its ISBN before publishing it; that failure causes book identification problems for libraries, booksellers, and readers. For example, ISBN0-590-76484-5 is shared by two books – Ninja gaiden®: a novel based on the best-selling game by Tecmo (1990) and Wacky laws (1997), both published by Scholastic.
Most libraries and booksellers display the book record for an invalid ISBN issued by the publisher. The Library of Congress catalogue contains books published with invalid ISBNs, which it usually tags with the phrase "Cancelled ISBN". However, book-ordering systems such as Amazon.com will not search for a book if an invalid ISBN is entered to its search engine.OCLC often indexes by invalid ISBNs, if the book is indexed in that way by a member library.
Only the term "ISBN" should be used; the terms "eISBN" and "e-ISBN" have historically been sources of confusion and should be avoided. If a book exists in one or more digital (e-book) formats, each of those formats must have its own ISBN. In other words, each of the three separate EPUB, Amazon Kindle, and PDF formats of a particular book will have its own specific ISBN. They should not share the ISBN of the paper version, and there is no generic "eISBN" which encompasses all the e-book formats for a title.
EAN format used in barcodes, and upgrading
Currently the barcodes on a book's back cover (or inside a mass-market paperback book's front cover) are EAN-13; they may have a separate barcode encoding five digits called an EAN-5 for the currency and the recommended retail price. For 10-digit ISBNs, the number "978", the Bookland "country code", is prefixed to the ISBN in the barcode data, and the check digit is recalculated according to the EAN-13 formula (modulo 10, 1x and 3x weighting on alternating digits).
Partly because of an expected shortage in certain ISBN categories, the International Organization for Standardization (ISO) decided to migrate to a 13-digit ISBN (ISBN-13). The process began on 1 January 2005 and was planned to conclude on 1 January 2007. As of 2011, all the 13-digit ISBNs began with 978. As the 978 ISBN supply is exhausted, the 979 prefix was introduced. Part of the 979 prefix is reserved for use with the Musicland code for musical scores with an ISMN. The 10-digit ISMN codes differed visually as they began with an "M" letter; the bar code represents the "M" as a zero (0), and for checksum purposes it counted as a 3. All ISMNs are now thirteen digits commencing 979-0; 979-1 to 979-9 will be used by ISBN.
Publisher identification code numbers are unlikely to be the same in the 978 and 979 ISBNs, likewise, there is no guarantee that language area code numbers will be the same. Moreover, the 10-digit ISBN check digit generally is not the same as the 13-digit ISBN check digit. Because the GTIN-13 is part of the Global Trade Item Number (GTIN) system (that includes the GTIN-14, the GTIN-12, and the GTIN-8), the 13-digit ISBN falls within the 14-digit data field range.
Barcode format compatibility is maintained, because (aside from the group breaks) the ISBN-13 barcode format is identical to the EAN barcode format of existing 10-digit ISBNs. So, migration to an EAN-based system allows booksellers the use of a single numbering system for both books and non-book products that is compatible with existing ISBN based data, with only minimal changes to information technology systems. Hence, many booksellers (e.g., Barnes & Noble) migrated to EAN barcodes as early as March 2005. Although many American and Canadian booksellers were able to read EAN-13 barcodes before 2005, most general retailers could not read them. The upgrading of the UPCbarcode system to full EAN-13, in 2005, eased migration to the ISBN-13 in North America.
VD 16 (Verzeichnis der im deutschen Sprachbereich erschienenen Drucke des 16. Jahrhunderts, "Bibliography of Books Printed in the German Speaking Countries of the Sixteenth Century")
VD 17 (Verzeichnis der im deutschen Sprachraum erschienenen Drucke des 17. Jahrhunderts, "Bibliography of Books Printed in the German Speaking Countries of the Seventeenth Century")
License number (East German books) [de] (Book identification system used between 1951 and 1990 in the former GDR)
^Occasionally, publishers erroneously assign an ISBN to more than one title—the first edition of The Ultimate Alphabet and The Ultimate Alphabet Workbook have the same ISBN, 0-8050-0076-3. Conversely, books are published with several ISBNs: A German second-language edition of Emil und die Detektive has the ISBNs 87-23-90157-8 (Denmark), 0-8219-1069-8 (United States), 91-21-15628-X (Sweden), 0-85048-548-7 (United Kingdom) and 3-12-675495-3 (Germany).
^In some cases, books sold only as sets share ISBNs. For example, the Vance Integral Edition used only two ISBNs for 44 books.
^Some books have several codes in the first block: e.g. A. M. Yaglom's Correlation Theory..., published by Springer Verlag, has two ISBNs, 0-387-96331-6 and 3-540-96331-6. Though Springer's 387 and 540 codes are different for English (0) and German (3); the same item number 96331 produces the same check digit for both (6). Springer uses 431 as the publisher code for Japanese (4), and 4-431-96331-? also has a check digit of 6. Other Springer books in English have publisher code 817, and 0-817-96331-? would also have a check digit of 6. This suggests that special considerations were made for assigning Springer's publisher codes, as random assignments of different publisher codes would not be expected to lead by coincidence to the same check digit every time for the same item number. Finding publisher codes for English and German, say, with this effect would amount to solving a linear equation in modular arithmetic.[original research?]
^The International ISBN Agency's ISBN User's Manual says: "The ten-digit number is divided into four parts of variable length, which must be separated clearly, by hyphens or spaces", although omission of separators is permitted for internal data processing. If present, hyphens must be correctly placed. The actual definition for hyphenation contains more than 220 different registration group elements with each one broken down into a few to several ranges for the length of the registrant element (more than 1,000 total). The document defining the ranges, listed by agency, is 29 pages.
^"ISBN Ranges". isbn-international.org. 29 April 2014. Select the format you desire and click on the Generate button. Archived from the original on 29 April 2014. Retrieved 29 April 2014.
^See a complete list of group identifiers. ISBN.org sometimes calls them group numbers. Their table of identifiers now refers to ISBN prefix ranges, which must be assumed to be group identifier ranges.
^Hailman, Jack Parker (2008). Coding and redundancy: man-made and animal-evolved signals. Harvard University Press. p. 209. ISBN978-0-674-02795-4.