Community:Collections and Metadata/RecommendedFormats

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Note: nsdl_dc schema link provided. Naomi Dushay 02/09/06
Note: Summary of best practices added. Jenn Riley 10/11/05



Potential Metadata Formats for Use with OAI


Summary of Best Practices

  • Choose metadata formats to supplement simple Dublin Core that are expressed as an XML schema, and are common in communities to which your resources are of interest.

The use of multiple metadata formats (at least one in addition to the required simple Dublin Core) is strongly encouraged, and this list is a necessarily incomplete list of potential metadata formats for use with OAI. To see the range of metadata formats in use, see the Distinct Metadata Schemas report from the OAI Registry at the University of Illinois at Urbana-Champaign.

As stated in the [MultipleMetadataFormats Use of multiple formats is strongly encouraged] section, in order to used within the OAI protocol a metadata format must have an XML schema (xsd) associated with it. To that end, links to the xsd are also provided.


Simple Dublin Core

All items exposed via OAI are required to have simple (unqualified) Dublin Core metadata. Data providers should expose the best standards-compliant simple Dublin Core records for harvesting as possible. Simple Dublin Core, however, cannot express some of the complexities many data providers wish to communicate about their resources (and which service providers wish to know!). In this case, metadata in a more complex format should also be made available by the data provider in addition to simple Dublin Core records. The choice of additional formats should be made based on the robustness of description desired for the resources in question, and the commonly-used metadata schema in the community in which the resources will be primarily used. Any number of additional metadata schemas may be used in order to reach desired audiences.

The OAI DC XML Schema is available at

Some Other Metadata Formats with XML Schemas:

MODS: Metadata Object Description Standard

MODS may be a good option for an additional metadata schema to expose via OAI for data providers who:

  1. locally engage in descriptive practices heavily influenced by resource description standards in libraries, and,
  2. have as a primary audience for resources described via OAI records a community well-versed in library descriptive practices, yet also want robust records in a format accessible to service providers outside the core library community.

The MODS v.3.0 XML Schema is available at

Qualified Dublin Core

Qualified Dublin Core may be a good option for an additional metadata schema to expose via OAI for data providers who:

  1. have a need for more granularity of description than is available in simple Dublin Core but not a fundamentally different approach to resource description, and,
  2. use controlled vocabularies that they wish to specify within their metadata records, and,
  3. have resources of interest to many different knowledge communities with disparate descriptive metadata practices.

There does not exist a single canonical Qualified Dublin Core XML schema. However, a XML schema for Qualified DC can be created through the importation of the necessary namespaces and schemas.

One example of an XML schema for Qualified DC based on the Dublin Core schemas and concepts is the National Science Digital Library's "nsdl_dc":


MARCXML may be a good option for an additional metadata schema to expose via OAI for data providers who:

  1. locally describe resources in MARC according to AACR2r, and,
  2. have as a primary audience for resources described via OAI records the core library community.

The MARCXML XML Schema is available at

ETD-MS: Electronic Theses, and Dissertations Metadata Standard

ETD-MS may be a good option for an additional metadata schema to expose via OIA for data providers who:

  1. are primarily exposing metadata about electronic theses and dissertations.
  2. wish to contribute to aggregations of electronic theses and dissertations such as the Networked Digital Library of Theses and Dissertations

The ETD-MS XML Schema is available at

Metadata Formats with XML Schemas in Development

VRA Core

Visual Resources Association (VRA) Core is a "single element set that can be applied as many times as necessary to create records to describe works of visual culture as well as the images that document them." The current version, VRA Core 3, is available as an XML DTD. The Visual Resources Association Data Standards Committee is currently developing a new version, VRA Core 4, which will be available as an XML Schema. The tentative release date for VRA Core 4 is early 2006.

See for more information about VRA Core, version 3.


The Getty Research Institute is developing an XML Schema "to describe core records for works of art and material culture based on the Categories for the Description of Works of Art (CDWA) and Cataloging Cultural Objects: A Guide to Describing Cultural Works and Their Images (CCO)." Currently there is a draft of the elements, tags, and descriptions available in draft form.

See for more information.

Encoded Archival Description (EAD)

EAD is an option for providing expressive metadata for linking parts of archival collections to a collection-level description. The benefit in using EAD is that all parts or items in a collection are provided en masse, making sure that individually digitized items do not lose their context in regard to their relationship to the collection as a whole.

There is no official EAD XML Schema, although leaders within the EAD community are discussing its creation. Several EAD implementers have converted instances of the EAD 1.0 and EAD 2002 DTDs into XML Schema, however. See for an example from Princeton University.

See for more information about the EAD standard.

See also [NamespacesAndSchemas] for information on encoding multiple version of metadata in XML.

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