New metadata standards for digital resources: MODS and METS

Bulletin of the American Society for Information Science & Technology, Dec 2002/Jan 2003 by Guenther, Rebecca, McCallum, Sally

Prospective Uses

The need for a rich metadata standard such as MODS has been expressed by members of the digital library and related communities as they attempt to implement projects involving search and retrieval, management of complex digital objects, integrating metadata from library databases with other non-MARC sources and other functions.

The "Search/Retrieve Web Service" (SRW) in ZING (239.50 International Next Generation ) (www.loc.gov/z3950/ agency/zing/srwu/srw.html) is a proof-of-concept initiative to develop value-added search and retrieve applications built on 239.50 along with Web technologies - XML, SOAP/RPC and HTTP. It defines a search service that specifies metadata schemas for retrieval. Since it uses XML, an XML metadata schema is needed, and one compatible with library data such as MODS would be desirable.

The Open Archives Initiative Protocol for Metadata Harvesting (www.openarchives.org/) harvests MARC records from multiple systems and makes them available widely. Generally, the records have been available in MARC (using MARC tagging and syntax in MARCXML) or simple Dublin Core in XML. The Library of Congress is planning to incorporate MODS as an alternate format for its over 100,000 metadata records that describe various forms of material digitized for American Memory. This will allow for the export of richer metadata than the Dublin Core record, which drops much of the metadata, but provides simpler data than full MARCXML.

MODS may be used for original resource description that allows for rich description that is generally compatible with existing library data and is expressed in XML syntax. Because it includes a subset of MARC fields and repackages some of them, it is particularly useful for technician input.

An additional use of MODS is as an extension schema for descriptive metadata for a METS object, as detailed later in this paper.

Experimentation with MODS

Since MODS was officially made available in June 2002, experimentation is just beginning. In June 2002, MODS was frozen for a six-month trial, although suggested additions are being listed on the MODS website. The following describes a few sample experiments.

* The Library of Congress 'Audio-Visual Prototyping Project is exploring aspects of digital preservation for audio and video. This collaborative project is developing approaches for packaging digital content, with a focus on metadata (http://lcweb.loc.gov/rr/mopic/avprot/avprhome.html). The project is experimenting with METS for packaging the digital object and its metadata and is implementing MODS for use as its descriptive metadata schema, particularly because of the rich descriptions of relationships with other items that may be expressed. Where possible metadata is being reused from descriptive cataloging records in one of the Library's databases with minimal data loss. In some cases, original resource description is provided and a MODS template is used.

* MINERVA(Mapping the Internet: Electronic Resources Virtual Archive) is an experimental pilot developed to identify, select, collect and preserve websites (http:// lcweb. loc.gov/minerva/ minerva.html). LC is collaborating with the Internet Archive (Alexa), SUNY and the University of Washington to collect and archive websites, providing descriptive metadata that will be used to search, retrieve and analyze the archived collections. Metadata will be created for websites in the collection using the MODS schema because of its compatibility with MARC data, to be used in the search and retrieval system and later converted to MARC and added to the Library's online catalog.