The Dublin Core Metadata Element Set (DC), for which the current iteration is version 1.1 available at http://dublincore.org/documents/dces/, is a simplified schema for description of collections and works within collections.It was conceived in the 1990's to aid in resource discovery as the Internet was expanding and more resources became available. Specific intentions underlying DC are to provide a generic, simple, flexible, extensible, interoperable descriptive framework, or metadata schema, that sacrifices neither customization sufficient to describe works' unique properties nor the capability of integration into databases of records devised by other schemas.
DC comprises fifteen (15) elements, each of which may be extended and/or repeated to accommodate an institution's specific needs for description. The core set of elements comprises:
This set of metadata elements applies to all resources no matter the format, including formats once considered "special" such as Web sites, works of art, video- and audio-recordings, still images, numeric datasets, computer programs, manuscripts, and geographic information systems, as well as such traditional bibliographic formats as textual monographs and serials. The applicability of its base set of elements to any format defines DC's simplicity. The extensibility of each generic element to specific types defines DC's flexibility.
GPO employs Dublin Core for selected projects, typically for those associated with a digital repository that contains descriptive, technical, and administrative metadata apart from GPO's Catalog of U.S. Government Publications (CGP) and OCLC, the international consortial database to which GPO contributes. The first project to which GPO is applying DC is Internet Archive's Archive-It digital repository. Archive-It is "a web archiving service to harvest and preserve digital collections." Archive-It supplies storage centers and software by which subscriber institutions manage harvested content. Institutions contribute metadata to the repository via a supplied template of Dublin Core elements. GPO expects that its approach to the Archive-It pilot project will serve as the model for its future DC endeavors. To that end, the following customized data elements are recommended as constant elements in GPO's bibliographic data in DC projects:
- GPO Item Number: example 0573-F
- Superintendent of Documents Classification Number: example AE 2.106:
- Digital Collection Name: examples below
- Archived U.S. Government Web sites for the Federal Depository Library Program
- Note for Metadata/Administrative History: examples below
- Cataloged originally according to the Dublin Core Metadata Element Set, version 1.1, in the Archive-It digital repository and converted to MARC 21 by batch process for GPO's Catalog of U.S. Government Publications (CGP), [date of import].
- This retrospectively digitized content, provided by [source agency], was ingested into X's online repository, [repository name], authenticated, digitally preserved, and made available to the public on [date]. This online collection represents the entirety of the content provided by the source agency [or, source agency office].
- [Note to reviewers: the 2nd example is from FDsys, even those that project crosswalks from MARC to MODS/METS rather than DC]
- Subject Headings
- Preferentially employ Library of Congress Subject Headings as topical terms and Library of Congress Name Authority File names and titles as other subject terms
Once Dublin Core metadata elements and values for records in a given project are completed in a database apart from the CGP, then it is necessary to convert those DC records to RDA content elements in MARC21 structural format for inclusion in the CGP. The conversion process requires a cross-walk cue sheet, or mapping document, which serves as the basis for the code written by the LTIS senior programmer, who writes and edits the crosswalk program.