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1.8. Standard Number and Terms of Availability Area

International Standard Book Number

1) Existing standard numbering system. The International Standard Book Number (ISBN) system developed from the book numbering system introduced in the United Kingdom in 1967. The principles and procedures for international standard book numbering are now embodied in the International Organization for Standardization's Recommendation 2108. The purpose of the ISBN is to identify one title or edition of a title from one specific publisher by number for processing and inventory control. The ISBN is carried in the MARC record and has become an additional access point in the catalog record in many computer-based systems, including the system at the Library of Congress.

Each ISBN consists of ten digits and is divided into four parts as follows:
a) Group identifier. This identifies the national, geographic, or other similar grouping of publishers. The group identifier varies in length according to likely output of items in a group; the larger the output, the smaller the group identifier. Group identifiers are allocated by the International ISBN Agency in Berlin. A numerical list of group identifiers may be found at <http://www.isbn-international.org/en/identifiers/allidentifiers.html>.

b) Publisher identifier. This identifies a particular publisher within a group. The length of this part varies; the larger a publisher's output, the shorter the publisher's identifier. Publisher identifiers are allocated by group or national ISBN agencies.

c) Title identifier. This identifies a particular title or edition of a title published by a particular publisher. The length of this part depends upon the length of the publisher identifier. Title identifiers are usually assigned by the publisher.

d) Check digit. This is always the last digit of the number; it consists of a single digit, 0-9, or the capital letter X, which represents the number 10. The check digit is derived from a calculation on the other nine digits and is used in computer systems to validate numbers as a means of checking against errors in transcription.

2) Previous numbering system. Prior to the adoption of the existing system, Standard Book Numbers (SBN) consisted of nine digits. The only difference between ISBNs and SBNs is that the latter do not contain a group identifier. SBNs were used only in the United Kingdom and the United States. With the inception of the ISBN system, all nine-digit numbers present in the LC MARC database were transformed into ISBNs by the addition of an initial zero to each number by means of computer program. See below for information on expansion of the ISBN from 10 to 13 digits.


Each ISBN (valid or invalid) recorded in the bibliographic record together with any qualification and associated terms of availability constitutes a single incidence of the ISBN area. In cases of multiple numbers, one or more of which is invalid, relating to precisely the same manifestation (e.g., a valid and invalid number; multiple invalid numbers), record them all in the same 020 field. Always record a valid number ($a subfield) first followed by any invalid number(s) ($z subfield).

LC practice: Transcribe ISBNs that appear on CIP data sheets or on bibliographic resources. Transcribe first the number that is applicable to the manifestation being described; transcribe other numbers in the order presented. Do not transcribe prices or other terms of availability.

Always add the qualifier “(loose-leaf)” in cases of updating loose-leafs per 12.8E2.

LC practice: In general, add qualifiers to numbers only to provide information judged important or needed to clarify the relationship of the number to the manifestation, particularly in the case of multiple ISBNs recorded in one record. In addition to always adding the qualifier “(loose-leaf)” in cases of updating loose-leafs, some other examples of using qualification are:
1) to show a manifestation has been printed on permanent paper (sometimes indicated by the infinity symbol ( 4 );
2) to show type of binding if considered important;
3) in cases of multipart items, to show whether a number relates to the set as a whole or a particular volume in the set.

Prefer qualifiers found on the bibliographic resource itself when they are judged to convey a condition intelligibly. Use judgment to deal with unusual, complex situations or unusual phenomena.

The ISBN is being expanded from 10 digits to 13. The date for fully adopting ISBN 13 is January 1, 2007. The revised International Organization for Standardization (ISO) standard is due to be published at the beginning of 2005. Publishers then have two years to implement ISBN 13 fully into all aspects of their businesses. For the interim period between 2005 and 2007, publishers are encouraged to supply both an ISBN 10 and an ISBN 13 for the same manifestation, based on guidelines issued by the International ISBN Agency (IIA). Beginning in 2007 publishers will supply only ISBN 13.

LC practice: In response to the desire of publishers to begin supplying ISBN 13 prior to 2005 to be included in Cataloging in Publication (CIP) data for books to be published in the interim period and beyond, the Library of Congress will begin accommodating ISBN 13 on October 1, 2004.

For CIP and other bibliographic records created after October 1, 2004 and before January 1, 2007, that contain pairs of ISBN 13 and ISBN 10, group them by manifestation in repeated MARC 21 020 fields, with the ISBN 13 input preceding the ISBN 10, each number qualified as appropriate.

020 ## $a 9781873671000 (hardbound)
020 ## $a 1873671008 (hardbound)

Continue to follow the guidelines stated above for ISBN 10 except to insure clarity, qualify each ISBN 13/ISBN 10 pair by the manifestation to which it relates. Prefer the term used in the source when it is judged to convey a condition intelligibly. For a hardbound resource, there is no attempt to use a consistent term other than to use one that conveys the condition intelligibly. Continue the practice of giving the ISBN, now a pair, related to the manifestation represented by the bibliographic record first. Note: If only an ISBN 13 is provided without an ISBN 10, do not input the ISBN 13; during the period January 1, 2005-January 1, 2007 when ISBN 13 is provided it is always to be paired with ISBN 10.

The guidelines for printing ISBN pairs in a book call for grouping the pairs of numbers by manifestation, giving the ISBN 13 first with each number preceded by a print constant as follows:
ISBN-13: 978-1-873671-00-0
ISBN-10: 1-873671-008

Note that in cases of multiple pairs, the guidelines call for the pairs to be printed on separate lines down the page one pair after the other. This is in contrast to the current style used in CIP data (printed across the page as part of a single paragraph, each instance of an ISBN separated by a space-dash-space). If any books published prior to October 1, 2004 contain an ISBN 13/ISBN 10 pair, add any ISBN 13 or ISBN 10 or both as appropriate at the time the bibliographic record is updated to reflect the book.

Note that all ISBN 13 begin with the digits “978," and consist of 13 digits. Note also, that because of the different lengths of ISBN 10 and ISBN 13, the formula for calculating the check digit for each is different and will most often result in a different check digit.
Subpages (2): 1.8B2 1.8E1