History and Overview of ISBN
– The Standard Book Number (SBN) was developed in 1965 by WHSmith.
– The ISBN identification format was conceived in 1967 in the UK and 1968 in the US.
– The 10-digit ISBN format was developed by the ISO and published in 1970.
– The UK used the 9-digit SBN code until 1974.
– The International ISBN Agency is the registration authority for ISBN worldwide.
– Each edition and variation of a publication is assigned a separate ISBN.
– The ISBN is 13 digits long if assigned after 2007 and 10 digits long if assigned before.
– A 10-digit ISBN consists of four parts, while a 13-digit ISBN consists of five parts.
– The parts of a 10-digit ISBN are the GS1 prefix, registration group, registrant, publication, and check digit.
– The parts of a 13-digit ISBN are the prefix element, registration group element, registrant element, publication element, and check digit.

Issuing Process and Registration Groups
– ISBNs are issued by the registration agency responsible for each country or territory.
– The ranges of ISBNs assigned to a country depend on its publishing profile.
– Some ISBN registration agencies are funded by the government, while others are provided by bibliographic data providers.
– A directory of ISBN agencies is available on the International ISBN Agency website.
– In the United States, R. R. Bowker is responsible for ISBN issuance.
– The registration group element is a 1-to-5-digit number within a prefix element.
– Registration groups within the 978 prefix element include 0 or 1 for English-speaking countries, 2 for French-speaking countries, 3 for German-speaking countries, 4 for Japan, 5 for Russian-speaking countries, and 7 for China.
– Rare languages may have longer group elements.
– Within the 979 prefix element, registration groups have been assigned to the United States, France, the Republic of Korea, and Italy.
– The registration group 0 in the 979 prefix element is reserved for compatibility with ISMNs.

Statistics and Registrant Element
– The United States had 3.9 million registered ISBNs in 2020, making it the largest user of the ISBN identifier.
– Other countries with significant ISBN registrations in 2020 include the Republic of Korea, Germany, China, the UK, and Indonesia.
– The United States had over 39 million lifetime ISBNs registered in 2020.
– The ISBN format changed to 13 digits in 2007 to align with Bookland European Article Numbers.
– The International ISBN Agency assigns ISBNs to privately published books without an ISBN.
– The national ISBN agency assigns the registrant element and a series of ISBNs to the publisher.
– A book publisher is not legally required to assign an ISBN, but most large bookstores only handle publications with ISBNs.
– The International ISBN Agency maintains details of over one million ISBN prefixes and publishers in the Global Register of Publishers.
– Publishers receive blocks of ISBNs, with larger blocks allotted to those expecting to need them.
– A publisher may have different allotted registrant elements and there may be more than one registration group identifier used in a country.

ISBN-10 Check Digits
– The ISBN-10 check digit must range from 0 to 10 and the sum of the ten digits, each multiplied by its weight, must be a multiple of 11.
– The check digit is base eleven and can be an integer between 0 and 9, or an X.
– The ISBN-10 check digit method ensures that it will always be possible to detect common types of errors, such as a single altered digit or transposition of adjacent digits.
– Other types of errors, such as two altered non-transposed digits or three altered digits, may still result in a valid ISBN, although it is unlikely.
– The sum of all ten digits, each multiplied by its weight in ascending order from 1 to 10, is also a multiple of 11.
– Each of the first nine digits of the ISBN-10 is multiplied by its weight, descending from 10 to 2, and the sum of these products is found.
– The check digit is the number between 0 and 10 that, when added to the sum, makes the total a multiple of 11.
– Modular arithmetic can be used to calculate the check digit using modulus 11.
– The remainder of the sum when divided by 11 is computed, and the check digit is (11 minus the remainder) modulo 11.
– If the value required to satisfy this condition is 10, an X should be used as the check digit.

ISBN-13 Check Digits and Conversion
– The ISBN-13 check digit is not compatible with SBNs and will give a different check digit from the corresponding ISBN-10.
– The 13-digit code was required to be compatible with the EAN format, and hence could not contain an X.
– The ISBN-13 check digit method ensures the detection of common types of errors and provides protection against transposition.
– The sum of the digits multiplied by their weights will never be a multiple of 10 for an invalid ISBN-13.
– It is possible for other types of errors, such as two altered non-transposed digits or three altered digits, to result in a valid ISBN-13.
– To convert a 10-digit ISBN to a 13-digit ISBN, the prefix ‘978’ is added to the ISBN-10.
– The final checksum digit is recalculated using the ISBN-13 algorithm.
– The reverse process is possible, but only for numbers starting with the prefix ‘978’.
– ISBNs with other prefixes do not have a 10-digit equivalent.

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