Our discussion paper for MARBI on "Representation of the Dewey Decimal Classification (DDC) System in MARC 21 Formats" is now published on the Library of Congress web site. It will be discussed by MARBI (the ALCTS/LITA/RUSA Machine-Readable Bibliographic Information Committee) at its meeting on the morning of Saturday, 23rd June, at the ALA Annual Conference in Washington. The MARBI agenda is published here.
This discussion paper arises out of the redevelopment of the DDC Editorial Support System (ESS), which was discussed in an earlier blog. It affects the MARC 21 format because we want to use that format to represent Dewey, rather than the proprietary format currently used in the ESS. We will be using the MARC Classification format for Dewey number records and Manual note records, and the MARC Authority format to represent Relative Index terms and mapped headings from subject thesauri such as LCSH and MeSH. We are making this conversion because we want the Dewey data to be available in a format supported by an international standard, and one that supports flexible data representation. We also want the data to be more fully integrated with data in OCLC's WorldCat and related authority files.
Another motivation for the discussion paper is that the German and Austrian MARC communities are converting from their MAB format to MARC 21. They had developed ways of representing Dewey numbers and components of Dewey numbers in the MAB bibliographic format, and were looking to doing something similar in the MARC 21 format. Although the proposal for representing component parts of numbers in the MARC Bibliographic format arose from the German and Austrian MARC communities, we expect others will take advantage of these fields to encode information for enriched access to bibliographic records and metadata.
Some of the most important proposals in the discussion paper are:
(1) Representing internal tables using a new $y subfield. DDC has both external tables (Tables 1 to 6) and internal tables to provide notation for number building. Some examples of internal tables are those at 290, 333.7-333.9, 592-599, 616.1-616.9, 820.1-828, 913-919, and 930-990. Dewey can have internal tables within external tables, e.g., those at T1--08 and T3B--81-89, and this adds an extra layer of complication. Some Dewey classes and spans have several internal tables associated with them, particularly in literature, e.g., 810.1-818 and 820.1-828, which means that we need to refer to each of those internal tables separately. What we are suggesting is the use of $y subfield in the MARC Classification format to identify specific internal tables in appropriate fields such as the 153 field of the Classification format.
(2) Inclusion of component parts of numbers in bibliographic records. The MARC 21 Classification format has a 765 field to represent the component parts of classification numbers built with add instructions, add tables, etc. The German MAB format had a way of doing that for Dewey numbers in bibliographic records, but one which is quite different from the method used in MARC 21. The discussion paper suggest using a new 085 field in the MARC 21 Bibliographic format to do this, in a way similar to the 765 field in the Classification format.
Other suggestions that we are making for the MARC 21 format include:
(3) Identifying external table numbers in the Bibliographic format.
(4) Giving classification number edition and source information in the Bibliographic format.
(5) Marking optional numbers in the Bibliographic format.
(6) Changing the 082 field in the Bibliographic format so that additional information about Dewey numbers can be coded in the field. That additional information would include whether the number was a primary number (i.e., the single number that would be assigned following the instruction in the edition cited in subfield $2 or an additional number (or component part of a number) providing for extra subject access (e.g., a Table 2 number for geographic location).
(7) Giving segmentation information for Dewey numbers in the Classification format.
(8) Encoding topic information in some Classification format fields.
(9) Giving Dewey number hierarchy information in field 153 of the Classification format.
For fuller details, read the discussion paper already cited.
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