Proposal for an Encoding Standard for Computer-Readable Exchange of Geospatial Metadata

Project Title

Encoding Standard for Computer-Readable Exchange of Geospatial Metadata

Date of Proposal Submission

October 1, 1996, resubmitted May, 1997, Last revision, July 28, 1997

Type of Standard Proposed

By the terms of the Reference Model this is a Data Transfer Standard, although it may be considered for a guideline or implementation annex -- because it is fully dependent on -- the FGDC Content Standard for Digital Geospatial Metadata, which is a Data Useability Standard.

Submitting Organization

FGDC Clearinghouse Working Group

Point of Contact

Doug Nebert, Chair, Clearinghouse Working Group

FGDC Secretariat

590 National Center

Reston, VA 20192

Phone: (703) 648-4151



This standard defines methods for the encoding of FGDC metadata element structure and content for the purposes of search and retrieval and metadata exchange by declaring an unambiguous computer-readable and parseable format for use within the geospatial data community. The intent of the standard is to permit flexibility in the local capture and management of the metadata and to facilitate consistent access to and exchange of spatial metadata via the National Geospatial Data Clearinghouse and other sharing and publishing mechanisms such as the World Wide Web only where rigorous encoding standards are appropriate.


This proposed standard is to be applied as a preferred exchange format to transfer metadata entries in an ASCII-based form without loss of information or context for the purposes of import and export by Clearinghouse software. It is intended for use among users of FGDC metadata, between metadata producers, editors, and Clearinghouse service providers where the exchange of full content of metadata is required. It is not intended for use as a presentation format. When used with style sheets, the encoding standard may optionally be used to systematize the presentation of FGDC metadata in compatible software and word processing packages. It is not designed to define the internal format of the metadata within a metadata management system or the default presentation format of the metadata, but is intended to assist in the loading (import) and reporting from (exporting) metadata from such systems.


Without implementation guidance the Content Standards for Digital Geospatial Metadata have been extremely difficult to formalize in an interoperable way. Specific objectives for the Clearinghouse have been to make metadata searchable by specific characteristics and to be rendered in familiar ways by different people. Through software and by example this has been done, but without formalization the ability for users to develop metadata in one system and use it in another has been unrealized. Furthermore, the indexing and service of searchable metadata requires that the various fields be parseable and discoverable. An encoding standard would promote the exhange, re-use, and even editing of metadata by different individuals and facilitate its processing in information servers.

Development Approach

The Encoding Standard is a brief statement formalizing the encoding of what already exists in the Content Standard using the ISO-8879:1986 Standard Generalized Markup Language (SGML). The development of the Document Type Declaration (DTD) or formal SGML structure was derived by direct conversion of the production rules of the Content Standards for Digital Geospatial Metadata. Metadata entries prepared using this DTD were tested in existing SGML parsers to assure structural validation of the metadata. Existing production rules or "grammar" of the Content Standard are adhered to, thus this standard documents a method of implementation for a specific purpose. By using existing standard, this methodology may be readily applied to extensions or modifications to the existing metadata content standard. The production of SGML is already supported by the FGDC metadata parser (mp) software for the current version of the metadata content standard.

Related Standards

Content Standards for Digital Geospatial Metadata, 1994. This is the reference standard to which this encoding format applies.

Standard Generalized Markup Language, SGML, ISO-8879:1986 This describes the standard methods by which Document Type Declarations (DTDs) are declared and used and what the formal tags within SGML are.

Geographic Information/Geomatics - Metadata, ISO-15046-15(Draft) The metadata portion of the ISO standard includes an informative annex on the suggested encoding of international geospatial metadata that is harmonized with this standard.

This standard is not intended to supercede de-facto conventions for the exchange of geospatial metadata but to promote a systematic format for the encoding and machine-readable exchange of metadata. There are no known formal standards for the encoding and exchange of digital geospatial data recognized by national or international standards bodies.

Development and Completion Schedule

Completed in October 1996 for Version 1.0 of the Content Standard.

Resources Required


Potential Participants

Membership of the Clearinghouse and Metadata Working Groups of the FGDC. This includes endorsement through Clearinghouse and metadata management tools by the following federal agencies:

  • U.S. Geological Survey
  • National Oceanic and Atmospheric Administration
  • U.S. Fish and Wildlife Service
  • NASA Global Change Master Directory Project
  • U.S. Department of the Navy, Naval Research Laboratory

the following state and local agencies:

  • Alaska Geographic Data Committee
  • Wisconsin State Cartographers Office (WISCLINC)
  • Montana State Library
  • North Carolina Corporate Geographic Data Base
  • Nebraska Natural Resources Commission
  • State of Ohio OGRIP
  • Pennsylvania State University
  • Texas Natural Resources Information System
  • University of Kansas
the following international coordination efforts:

  • Catalogue Interoperability Profile, European Space Agency and Committee on Earth Observing Satellites
  • Canada Earth Observation Network (CEONet)
  • Africa Data Dissemination Service (AID Project)
  • Inter-American Geospatial Data Network (AID Project)
  • Biological Resource Maps, Costa Rica
  • CODEPLAN, Federal District of Brazil
  • Global Environmental Information Locator Service, Centre for Earth Observation, Italy
and the following producers of metadata management software:

  • Blue Angel Technologies (Metadata Manager, Metadata Server)
  • Center for Networked Information Discovery and Retrieval (Isite)
  • Mitre Corporation (metadata tool revision)
  • USGS Biological Resources Division and Geologic Division (metadata parser - mp and MetaMaker)
  • Army Corps of Engineers, CRREL (Corpsmet-95)

Other Targeted Authorization Bodies

This standard is tightly coupled to the Content Standard, and as such, has been included topically as an Informative Annex to the ISO TC-211 WG5 Metadata activity.