We often get asked how frequently we update the DDC. The short answer is, we update the DDC continuously. We have a short-term and long-term editorial work plan; we roll out updates from the short-term plan regularly, and the long-term plan as they become available. Of course, lots of new topics come up that don’t appear on any plan and need to be addressed as they emerge. We distribute updated web versions quarterly, and produce snapshots of the underlying databases in print editions about every seven years. Our web versions (WebDewey and Abridged WebDewey, respectively) are available by subscription; we also make XML versions of the underlying databases available to translators, research projects, and other licensees.
You can get a sense of changes to categories by visiting the New and Changed Entries on the Dewey web site. We announce selected updates on the web site; users have to consult the web versions of the DDC to see all changes to the underlying databases. Recent changes have ranged from updates to the treatment of GIS/GPS to an extended version of the area table for ancient and modern Italy that we just completed with the advice of our Italian translators. You can get a flavor of the mapped terminology we announce on a biweekly basis by looking at the LCSH-DDC mappings on the same web site.
Here are some ballpark statistics on additions to the full edition since we published a new print snapshot of the database (DDC 22) in late 2003:
- New categories: ~120/year (new table and schedule numbers, e.g., the new expansion for terrorism at 363.325 introduced in November 2005)
- Additional synthesized numbers: ~450/year (numbers built using the number building instructions to represent concepts explicitly as the need arises, e.g., the synthesized numbers we added for Hurricane Katrina; we added them last year, but you can see an explanation of how the numbers are constructed in the recent blog on hurricanes)
- New mapped terminology from Library of Congress Subject Headings: ~1800/year (e.g., Semantic Web 025.04, Crunk (Music) 782.421649, Wheelchair rugby 796.333)