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ISBN

The barcode of an ISBN . The bar code (machine readable) represents the 13 digit ISBN (in this example : ISBN 978-81-7525-766-5 ). The human readable 10 digit ISBN 81-7525-766-0 is printed on top and the 13 digit version at the bottom. Both the numbers refer to the same book.
The barcode of an ISBN . The bar code (machine readable) represents the 13 digit ISBN (in this example : ISBN 978-81-7525-766-5 ). The human readable 10 digit ISBN 81-7525-766-0 is printed on top and the 13 digit version at the bottom. Both the numbers refer to the same book.

The International Standard Book Number, or ISBN (sometimes pronounced [ˈɪzbən]), is a unique[1] identifier for books, intended to be used commercially. The ISBN system was created in the United Kingdom in 1966 by the booksellers and stationers WH Smith and originally called Standard Book Numbering or SBN (still used in 1974). It was adopted as international standard ISO 2108 in 1970. A similar identifier, the International Standard Serial Number (ISSN), is used for periodical publications such as magazines. From January 1, 2007, ISBNs will be 13 digits long.[2] The TC 46/SC 9 is responsible for the standard.

Contents

[edit] Overview

Each edition and variation (except reprints) of a book receives its own ISBN. The number is either 10 or 13 (from 1 January 2007) digits long, and consists of four or five parts:

  1. if 13-digit ISBN, a GS1 Prefix, either 978 or 979
  2. the country of origin or language area code, [3]
  3. the publisher,
  4. the item number, and
  5. a checksum character or check digit.

The different parts can have different lengths and are usually separated by hyphens or spaces - the international ISBN agency "ISBN User Manual" states "The ten-digit number is divided into four parts of variable length, which must be separated clearly by hyphens or spaces" although it allows these to be omitted for internal data processing as the prefix code ensures that no two codes start the same way. If present, hyphens must be placed correctly;[4] however they are not always practically sufficient for identifying the publisher since the listing of all assigned publisher identifiers The Publishers International ISBN Directory (PIID) is a chargeable periodical publication.

The country field is 0 or 1 for English speaking countries, 2 for French speaking countries, 3 for German speaking countries, 4 for Japanese, 5 for Russian, etc. (The original SBN lacked the country field, but prefixing 0 to a 9-digit SBN creates a valid ISBN.) The country field can be up to 5 digits long; 99936 for instance is used for Bhutan.[5]

The publisher number is assigned by the national ISBN agency, and the item number is chosen by the publisher. There is, in general, no requirement for a publisher to assign an ISBN to a book nor for that book to display its number — but see below for the exception in China. However, many bookstores will only deal with items bearing an ISBN.

Publishers receive blocks of ISBNs, with larger blocks going to publishers that are expected to need them; a small publisher might receive ISBNs consisting of a digit for the language, seven digits for the publisher, and a single digit for the individual items. Once that block is used up, the publisher can receive another block of numbers, with a different publisher number. As a consequence, different publisher numbers may correspond to the same publisher.

[edit] Check digit in ISBN 10

The International ISBN Agency[6] in its official manual states that the 10-digit ISBN check digit,[7] which is the last digit of the 10 digit ISBN, is calculated on a modulus 11 with weights 10 to 2, using X instead of 10 where ten would occur as a check digit. This means that each of the first nine digits of the 10-digit ISBN—excluding the check digit itself—is multiplied by a number in a sequence from 10 to 2 and that the resulting sum of the products, plus the check digit, must be divisible by 11 without a remainder.

By this method the calculation for the 10-digit ISBN whose first nine digits are 0-306-40615 would be done thus:

  10×0 + 9×3 + 8×0 + 7×6 + 6×4 + 5×0 + 4×6 + 3×1 + 2×5
=  0  +  27  +  0  +  42 +  24 +  0  +  24 +  3  +  10
= 130
The next complete multiple of 11 is 12×11 = 132
132 - 130 = 2

So the check digit is 2, and the complete sequence is ISBN 0-306-40615-2.

A second method to find the check digit is by first multiplying each digit of the 10-digit ISBN by that digit's place in the number sequence from 1 to 9, with the leftmost digit being multiplied by 1, the next digit by 2, and so on. Next, take the sum of these multiplications and calculate the sum modulo 11, with "10" represented by the character "X". For example, to find the check digit for the 10-digit ISBN whose first nine digits are 0-306-40615:

  1×0 + 2×3 + 3×0 + 4×6 + 5×4 + 6×0 + 7×6 + 8×1 + 9×5
=  0  +  6  +  0  +  24 +  20 +  0  +  42 +  8  +  45
= 145
= 13×11 + 2

So the check digit is 2, and the complete sequence is ISBN 0-306-40615-2.

For those more mathematically inclined, it should be noticed that a 10-digit ISBN's check digit is "actually" computed via dot products. (1,2,3,4,5,6,7,8,9) dot (x,x,x,x,x,x,x,x,x) mod 11 = check digit.

The two most common errors which occur when handling an ISBN (e.g., typing it in or writing it down) are an altered digit or transposition of adjacent digits. Since 11 is a prime number, the ISBN check digit method ensures that these two kinds of errors will always be detected. If the error occurs at the publisher, and is not detected, the book can be issued with a theoretically invalid ISBN.[8]

[edit] Check digit in ISBN 13

The International ISBN Agency's official 2005 manual[9] covering some ISBNs issued beginning January 2007, describes how the 13-digit ISBN check digit is calculated.

Calculating an ISBN 13 check digit requires that each of the first twelve digits of the 13-digit ISBN — excluding the check digit itself — be multiplied alternately by 1 or 3. Next, take the sum modulo 10 of these products. This result is subtracted from 10. The result is the check digit. If the check digit calculates to 10, 0 is used.

For example, an ISBN-13 of 978-0-306-40615-__ is calculated:

  9×1 + 7×3 + 8×1 + 0×3 + 3×1 + 0×3 + 6×1 + 4×3 + 0×1 + 6×3 + 1×1 + 5×3
=  9  +  21 +  8  +  0  +  3  +  0  +  6  +  12 +  0  +  18 +  1  +  15
= 93
93 / 10 = 9 remainder 3
10 – 3 = 7

So the check digit is 7, and the complete sequence is ISBN 978-0-306-40615-7.

An ISBN-13 of 978-0-356-42615-__ is calculated:

  9×1 + 7×3 + 8×1 + 0×3 + 3×1 + 5×3 + 6×1 + 4×3 + 2×1 + 6×3 + 1×1 + 5×3
=  9  +  21 +  8  +  0  +  3  +  15 +  6  +  12 +  2  +  18 +  1  +  15
= 110
110 / 10 = 11 remainder 0
10 – 0 = 10
Report "0" for a result of 10

So the check digit is 0, and the complete sequence is ISBN 978-0-356-42615-0.

Unlike ISBN-10, this check system will not always detect transposition errors.

[edit] EAN format used in barcodes, and planned upgrade

Currently, the barcodes found on the backs of books (or inside front covers of mass-market paperbacks) are EAN-13; they may have a separate barcode encoding five digits for the currency and recommended retail price.[10] "978" the Bookland "country code", is prepended to the ISBN in the barcode data, and the check digit is recalculated according to the EAN13 formula (modulo 10, 1x, and 3x weighting on alternate digits).

Partly because of a pending shortage in certain ISBN categories, the International Organization for Standardization (ISO) started migrating to a thirteen-digit ISBN (sometimes referred to as ISBN-13) in a process that began on 1 January 2005 and should finish on 1 January 2007.[11] Existing ISBNs will be prefixed with "978" (and the check digit recalculated); as the "978" ISBNs are exhausted, the "979" prefix will be introduced. This is expected to happen more rapidly outside the United States. ("979" was originally the "Musicland" code for musical scores bearing an ISMN, however ISMN codes will be different in that visually they start with an M, and while the bar code will represent the M as a 0, for checksum purposes it will count as a 3.) Note that publisher identification codes are unlikely to be the same in 978 and 979 ISBNs. Moreover, the old ISBN check digit for a book (when they were 10 digits long) is generally not going to be the same as the book's new check digit in its 13-digit ISBN.

Since the new 13-digit ISBNs will be identical (apart from group breaks) to the EAN barcoded format of any existing 10-digit ISBNs, this process will not break compatibility with any existing barcodes. This means that moving to an EAN-based system will allow booksellers to use a single numbering system for both book and non-book products without breaking backwards compatibility with existing ISBN-based information, and with only minimal changes to their information technology (IT) systems. For this reason, many booksellers, including Barnes & Noble, have started the process of phasing out usage of ISBNs in favour of using EAN codes as early as March 2005. Although many booksellers in the U.S. and Canada have been able to read EAN-13 barcodes for many years, most general retailers could not prior to 2005. The upgrading of the UPC barcode system to full EAN-13 in 2005 makes the transition to ISBN-13 all the easier in North America.

There is one retrograde aspect of the adoption of the EAN barcode system for books: it is less capable of detecting errors by comparison to the old ISBN system (before January 1, 2007). The EAN barcode uses modulus 10, and while the system of weights (alternating 1 and 3) lets EAN detect any single digit error, not all adjacent transposition errors can be detected (one in nine cannot). This is the best that can be achieved with a single decimal check digit.

[edit] The ISBN check digit in use

A variety of policies exist around the use of the ISBN check digit within the publishing industry and libraries. Publishers sometimes fail to check the ISBNs on their books before issuing them, introducing a problem for libraries, booksellers, and readers.

Most libraries and booksellers display the book record for an invalid ISBN if that is how it was issued by the publisher. The Library of Congress has in its catalog a number of books published with invalid ISBNs, though it often tags the resulting fields with the phrase "Cancelled ISBN".

Some book-ordering systems such as Amazon.com will not even attempt to search for a book if given an invalid ISBN.

[edit] ISBNs and book censorship in China

ISBNs are used as a means of book censorship in the People's Republic of China. For a printer to legally print a run of books, they must have an ISBN, which are assigned in blocks to state owned publishing houses. However, since the 1990s, this means of censorship has become much less effective as state publishing houses, which have been weaned from government subsidy like all state owned enterprises, will now sell ISBNs to the highest bidder without regard to the content.

[edit] Footnotes

  1. ^ Occasionally publishers will use an ISBN in error for more than one title (for example, the first edition of "The Ultimate Alphabet" and "The Ultimate Alphabet Workbook" have the same ISBN 0-8050-0076-3). Conversely, books can be published with multiple ISBNs: A German as a second language edition of Emil und die Detektive has the following ISBNs: 87-23-90157-8 (Denmark), 0-8219-1069-8 (United States), 91-21-15628-X (Sweden), 0-85048-548-7 (England) and 3-12-675495-3 (Germany).
  2. ^ As explained in this summary document from ISO
  3. ^ Some books have more than one language area code, e.g. A.M.Yaglom, Correlation Theory... , published by Springer Verlag has ISBN 0-387-96331-6 and ISBN 3-540-96331-6. Note that in this case Springer has publisher codes for both language areas, and chooses to use the same item number.
  4. ^ See hyphenation instructions at the isbn.org web site.
  5. ^ See a complete list of group identifiers.
  6. ^ http://www.isbn-international.org/
  7. ^ http://www.isbn-international.org/en/userman/download/ISBNmanual.pdf
  8. ^ For example I'saka: a sketch grammar of a language of north-central New Guinea. Pacific Linguistics. ISBN "0-85883-554-4".
  9. ^ Available in PDF here
  10. ^ For a detailed description of the EAN13 format, http://www.barcodeisland.com/ean13.phtml.
  11. ^ There is a FAQ document about this change.

[edit] See also

  • ASIN (Amazon Standard Identification Number)
  • CODEN (An identifier of serials, still in use by libraries, but replaced by ISSN for any new work)
  • DOI (Digital Object Identifier)
  • ISAN (International Standard Audiovisual Number)
  • ISMN (International Standard Music Number)
  • ISRC (International Standard Recording Code)
  • ISSN (International Standard Serial Number)
  • ISWC (International Standard Musical Work Code, see http://iswc.org )
  • Library of Congress Control Number
  • SICI (Serial Item and Contribution Identifier)
  • Wikipedia:ISBN, use of ISBN on Wikipedia

[edit] External links

National and international agencies
Online tools
Can also use it to verify ISBNs to see if they're valid. Assures compliance with the full ISBN spec, not just the check digit.