Metadata Standards

Data and information resources are generated by diverse user communities and the metadata required to describe these resources are equally diverse. Metadata must adequately describe data in terms useful to user communities and appropriate to the data or information resource. Over time, an array of diverse metadata formats have evolved which enable various organiztions, agencies, and user communities to tailor metadata to specific needs. Standardizing these metadata provide uniformity to the information presented, which facilitates information sharing among various organizations and agencies.

Several standardized metadata formats exist:

• Anglo-American Cataloging Rules (AACR2): A standard by which library materials (such as books, audio recordings, and films) are organized and described. Descriptions of these items typically have headings and/or uniform titles to make the items more accessible in catalog searches. The rules for description are based on the general framework for description of library materials, the General International Standard Biblio-graphic Description agreed upon between the International Federation of Library Associations and Institutions and the Joint Steering Committee for revision of AACR.
  

• Content Standards for Digital Geospatial Metadata (CSDGM): Addresses the need to determine common terminology for geospatial metadata and to define the minimum set of metadata elements needed to describe a spatial data resource. It was approved at the June 8, 1994 meeting of the Federal Geographic Data Committee (FGDC), and by Executive Order 12906, "Coordinating Geographic Data Acquisition and Access: The National Spatial Data Infrastructure," which instructs U.S. federal agencies to use the standard to document new geospatial data beginning in 1995. The FGDC developed this standard to help identify sources of spatial data and provide access to data through the emerging National Information Infrastructure.
  

• Directory Interchange Format (DIF): The data structure for directory metadata developed by NASA and maintained by the Interagency Working Group on Data Management for Global Change (IWGDMGC). The format, originally designed to describe satellite and other remotely-sensed data, suggests metadata elements for describing data, prescribes content values for selected elements, and provides a structure for transferring metadata among information systems. These metadata are descriptions which enable a user to make an initial determination of whether or not the data set may contain information of relevance.
  

• Government Information Locator Service (GILS): As part of the National Information Infrastructure (NII), GILS provides a framework for individuals and organizations to improve access to their information resources. The U.S. federal government implementation of GILS includes a publicly-accessible catalog of federal information resources, each described using a specific metadata format. GILS supplements other government and commercial information dissemination mechanisms, and uses international standards for information search and retrieval so that information can be retrieved in a variety of ways.
  

• Machine-Readable Cataloging (MARC): A metadata standard used by the library community to facilitate exchange of catalog records which employ the Anglo-American Cataloging Rules to describe a myriad of resources.

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