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

* The University of Chicago Press is implementing a project to support the development of the Chicago Digital Distribution Center, which would be built upon its traditional distribution center and involves making digital books available for distribution. The Press harvests MARC records to enhance searchability and for export to their client presses, converting them into MODS for more concise description and more understandable language-based tags.

* The California Digital Library is establishing a generic METS repository infrastructure to help manage the digital objects in its control. A project provides for search and display of 1,500 records for books published online by the CDL on behalf of the University of California Press. Records are extracted from the union catalog and transformed to MODS, then inserted into the METS record. Specified fields are used for indexing and searching as well as in response to an Open Archives Initiative Harvesting Protocol query.

METS

The Metadata Encoding and Transmission Standard (METS) (www.loc.gov/standards/mets) grew out of several experimental 1990s digital projects. In February 2001, the Digital Library Federation convened a meeting of experts from several projects to evaluate what had been learned with respect to metadata and to decide how to go forward. Out of that meeting came the idea for METS, an XML document that packages the metadata associated with a digital resource - the descriptive, administrative, structural, rights and other data needed for retrieving, preserving and serving up digital resources. Then, in a little over a year the METS XML schema was developed, a maintenance structure set up and experimentation worldwide began.

METS metadata is essential for a digital material repository, where digital resources - over 7 million at LC alone are stored along with information about the resources. A repository, which can take many configurations, is the instrument for access and preservation of the objects. The METS data is also important for the interchange of digital objects for viewing and use by other systems. If the digital resource has with it the METS description, the file should be usable for many activities at the receiving system.

Characteristics of METS

METS is an open standard, not a proprietary one. Library system staff and librarians who also participate in developments in the Internet community are constructing it. Jerome McDonough of NYU serves in the critical role of editor-inchief of the METS XML schema. The Library of Congress has agreed to serve as the maintenance agency for the standard - building a website for METS, supporting an open listserv for implementers and working on extension schema. Recently.an editorial board was formed of major contributors to the development thus far with the intent to identify and bring in global partners. The schema is now complete and stable enough to consider taking it to a formal standards body such as ISO or NISO.

The structure of the METS schema is highly flexible and relatively simple. It is conceptually six modules that contain and/or point to the different types of metadata needed for a digital resource. In several of the modules the METS standard does not define the metadata elements and tags to be used. It allows the user to choose a standard "extension" schema and identify and use it. For several modules it allows the metadata to reside outside the package, pointed to from within the METS document. These features exemplify the flexibility of METS.