Our colleagues at Deutsche Nationalbibliothek (DNB) have just alerted us to the implementation of a change made in the representation of DDC Sachgruppen (MARC source code "sdnb") in the MARC 21 bibliographic format. DDC Sachgruppen is an authorized German derivative work based on selected DDC 22 top-level classes (including some below the three-digit level). Its primary use is to organize the national bibliographies of Germany, Austria, and Switzerland. The original language of DDC Sachgruppen is German; it has also been translated into English, French, Italian, and Rhaeto-Romansch to accommodate the language requirements of the Swiss national bibliography. See below for an illustration of its relationship to the rest of the DDC 22 family of editions, language versions, and derivative works.
When initially introduced, DDC numbers from the DDC Sachgruppen were represented in the 084 Other Classification Number field, with the code "sdnb” in $2 Number source. As of two weeks ago, DDC numbers from DDC Sachgruppen will now appear in subfield $2 in fields 082 Dewey Decimal Classification Number and 083 Additional Dewey Decimal Classification Number with 1st indicator 7 (Other edition specified in subfield $2): $2 22sdnb. When the DDC Sachgruppen is updated to reflect DDC 23 content, the edition number in subfield $2 will change to "23sdnb." For more information, see the 23 October 2012 entry at http://www.dnb.de/EN/Service/DigitaleDienste/Datendienst/rundschreibenDatendienst.html.
It is worth noting that this change arose from a conversation we had with Reinhold Heuvelmann (DNB) during the ALA Annual Conference in New Orleans in June 2011 about the general schema for representing DDC editions, language versions of DDC editions, and derivative works based on the DDC. DNB has been an important partner in discussions of representation of classification data and worked with us on the development of the aforementioned 083 field, plus the 085 Synthesized Classification Number Components field. Most recently, DNB was a key collaborator (with LC and OCLC) on the new 883 Machine-generated Metadata Provenance field.