TLC and 13-digit ISBNs

Updated 12/28/2004

In October 2004, the Library of Congress and other cataloging sources began distributing MARC records containing 13-digit ISBN numbers in accordance with new standards published by the International ISBN Agency.  The change rivals Y2K in many ways. TLC has thousands of installed users, some using its integrated automation system, Library Solution, others using standalone products, such as ITS for Windows, ITS MARC, and NetPAC. All are affected.

Essentially, TLC has adopted the policy of accepting ISBN data in any format provided, indexing it as if it were a new format ISBN (as 13 digits), and presenting it as originally entered. This approach is intended to make the conversion as transparent as possible to the end user, ensuring searchability while leaving the source data intact.

A myriad of TLC databases and internal processes support the needs of these communities. The ISBN is so integral to many of these processes that some had to be rewritten from the ground up. Some are being modified as we go forward and learn of various approaches being adopted by the library community and its supporting vendors. Currently, all of these developments are on schedule. However, the approach required for each product varies slightly:

  • Library Solution users will receive full-level 13-digit ISBN support with version 3.3, scheduled for release in the second quarter of 2005. All ISBNs found on all publications worldwide will be searchable in this version, even those targeted for use after 2007. For users awaiting the installation of this version, 13-digit ISBNs should be searched by omitting the "978" prefix and entering only the first nine digits of the ISBN (leaving off the check digit).
  • NetPAC and ITS MARC both inherently support the search and retrieval of records using either a 10- or a 13-digit search argument. However, the ISBN entered by the user and the original cataloger must match. This is possible if the original cataloger entered the ISBN in both formats, but this is not a universal practice, and it is not certain that all such catalogers will calculate the converted check digit accurately. Thus, these programs are being modified to interpret search arguments entered either as 10- or 13-digits, and find records entered either way. This change will be implemented in the first quarter of 2005. Until that time, ISBN searches will succeed only if cataloged correctly by the original cataloger. However, both before and after the change, all searches should be entered exactly as found on the publication, whether 10 or 13 digits.
  • ITS for Windows users received a software update (Version 3.75) in December 2004 that carries them to December 2006. By that time, the ITS program will be superseded by its next-generation, Unicode-compliant counterpart, BiblioFile, which will use 13-digit ISBN indexes but accept either 10- or 13-digit search arguments. As with all other products, data in the MARC record will be preserved as entered. ITS 3.75 users should enter ISBNs exactly as found on the publication. Users of earlier versions should upgrade to 3.75 by requesting an update CD from TLC or downloading the new version from the ITS MARC website.

These software and internal processing changes will ensure that all users have access to MARC records regardless of how the ISBN was originally entered or subsequently modified, simply by entering the ISBN as found. The software rollout schedule for Library Solution implies that some users will not see these changes for some months into the future. For these users, ISBN searches will still be possible, but 13-digit search arguments will have to be truncated to the first 10 digits to support a successful search. In some cases, these users will have to select the correct record from among multiples in a result set. While the total number of such records could theoretically be as high as 99, such large result sets are not expected for several months into 2005, allowing such users ample time to schedule a software upgrade.

For more information about this change and the approach being taken by various organizations, visit:

Library of Congress:

International ISBN Agency:

Book Industry Study Group:


Questions about this information should be directed to TLC Support at You may also phone our Support Team by dialing 800-852-4911 or 304-229-0100.

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