The objectives of the standard are to provide a common set of terminology and definitions for the documentation of digital geospatial data. The standard establishes the names of data elements and compound elements (groups of data elements) to be used for these purposes, the definitions of these compound elements and data elements, and information about the values that are to be provided for the data elements.
The major uses of metadata are:
- to maintain an organization's internal investment in geospatial data,
- to provide information about an organization's data holdings to data catalogues, clearinghouses, and brokerages, and
- to provide information needed to process and interpret data to be received through a transfer from an external source.
The information included in the standard was selected based on four roles that metadata play:
- availability -- data needed to determine the sets of data that exist for a geographic location.
- fitness for use -- data needed to determine if a set of data meets a specific need.
- access -- data needed to acquire an identified set of data.
- transfer -- data needed to process and use a set of data.
These roles form a continuum in which a user cascades through a pyramid of choices to determine what data are available, to evaluate the fitness of the data for use, to access the data, and to transfer and process the data. The exact order in which data elements are evaluated, and the relative importance of data elements, will not be the same for all users.
This standard is intended to support the collection and processing of geospatial metadata. It is intended to be useable by all levels of government and the private sector. The standard is not intended to reflect an implementation design. An implementation design requires adapting the structure and form of the standard to meet application requirements.
The standard was developed from the perspective of defining the information required by a prospective user to determine the availability of a set of geospatial data; to determine the fitness and the set of geospatial data for an intended use; to determine the means of accessing the set of geospatial data; and to successfully transfer the set of geospatial data. As such, the standard establishes the names of data elements and compound elements to be used for these purposes, definitions of these data elements and compound elements, and information about the values that are to be provided for the data elements. The standard does not specify the means by which this information is organized in a computer system or in a data transfer, nor the means by which this information is transmitted, communicated, or presented to the user.
- The variety of means of organizing data in a computer, the differences among data providers to describe their data holdings because of varying institutional and technical capabilities, the rapid evolution of means to provide information through the Internet for different purposes, and the need to accommodate existing standards have guided the evolution of this decision. The FGDC is pursuing several implementation methods.
This standard is for the documentation of geospatial data. Executive Order 12906, "Coordinating Geographic Data Acquisition and Access: The National Spatial Data Infrastructure," was signed on April 11, 1994, by President William J. Clinton. Section 3, Development of a National Geospatial Data Clearinghouse, paragraph (b) states: "Standardized Documentation of Data. Beginning nine months from the date of this order, each agency shall document all new geospatial data it collects or produces, either directly or indirectly, using the standard under development by the FGDC, and make that standardized documentation electronically accessible to the Clearinghouse network. Within one year of the date of this order, agencies shall adopt a schedule, developed in consultation with the FGDC, for documenting, to the extent practicable, geospatial data previously collected or produced, either directly or indirectly, and making that data documentation electronically accessible to the Clearinghouse network." This standard is the data documentation standard referenced in the executive order.
The FGDC invites and encourages organizations and persons from State, local, and tribal governments, the private sector, and non-profit organizations to use the standard to document their geospatial data. A major difficulty in the geospatial data community is the lack of information that helps prospective users to determine what data exist, the fitness of existing data for planned applications, and the conditions for accessing existing data, and to transfer data to a user's system. This standard, developed with aid of broad public participation, will help to ease these problems and to develop the National Spatial Data Infrastructure.
4. Related Standards
The Spatial Data Transfer Standard (SDTS) was developed to allow the transfer of digital spatial data sets between spatial data software. The Content Standard for Digital Geospatial Metadata was developed to identify and define the metadata elements used to document digital geospatial data sets for many purposes. These include metadata to: 1) preserve the meaning and value of a data set; 2) contribute to a catalog or clearinghouse and; 3) aid in data transfer. Since the SDTS is a standard for data transfer, its primary metadata content is used to determine the fitness of the data set for the user's purpose. There is a close relationship between the Metadata Standard and the SDTS metadata elements contained in the Data Quality module, and in other locations inside of the SDTS transfer set. Since the Metadata Standard contains metadata used to search for digital spatial data sets through a clearinghouse (metadata for locating, describing access, use, and distribution), these elements may not be contained in the SDTS transfer set.
The Content Standard for Digital Geospatial Metadata uses to the maximum extent possible, existing International or National Standards, as documented in Office of Management and Budget Circular A-119 "Federal Participation in the Development and Use of Voluntary Consensus Standards and in Conformity assessment Activities." American National Standards referenced in the Content Standard for Digital Geospatial Metadata include the American National Standards Institute, 1975, Representations of universal time, local time differentials, and United States time zone reference for information interchange (ANSI X3.51-1975): New York, American National Standards Institute; American National Standards Institute, 1986, Representation for calendar date and ordinal date for information interchange (ANSI X3.30-1985): New York, American National Standards Institute; American National Standards Institute, 1986, Representations of local time of day for information interchange (ANSI X3.43-1986): New York, American National Standards Institute.
The June 8, 1994 FGDC Metadata Standard was used as the base document for International Organization for Standardization (ISO) 15046 Part 15. The draft ISO Metadata Standard 15046 Part 15 has had a number of changes made to it. At this time this revision was prepared, the ISO Metadata Standard was still in Committee Draft form and subject to significant change before final approval, therefore, is not identical to the current ISO draft but is thought to be consistent with it.
5. Standards Development Process
The Federal Geographic Data Committee (FGDC) initiated work on the first version of the standard in June, 1992, through a forum on geospatial metadata. At the forum, the participants agreed on the need for a standard on the information content of metadata about geospatial data. The committee accepted the offer of ASTM Section D18.01.05 to develop a draft information content standard. The draft was slightly revised, and offered for public review from October 1992 to April 1993. Extensive comments were received from the public. The FGDC Standards Working Group revised the draft. The revised draft was provided for further review and testing in July 1993. Refined drafts were offered for review and testing in January and March 1994. The first version was approved June 8, 1994.
- formally the American Society for Testing and Materials
Since the FGDC Metadata Standard was adopted, it has been implemented by numerous Federal, state, and local agencies, companies, and groups. It has also been used by other nations as they develop their own national metadata standards. Proposed changes to the Metadata Standard have been suggested during the time since it was issued. Further, an implementor's workshop was held specifically to discuss strengths, weaknesses, and proposed improvements. Drawing on this body of knowledge, the FGDC proposed to modify the current Metadata Standard.
The June 1998 version is fully backward compatible with and supersedes the June 8, 1994 version. The June 1998 version provides for the definition of Profiles (Appendix E) and extensibility through User Defined Metadata Extensions (Appendix D). The June 1998 version also modifies some production rules to ease implementation.
6. Maintenance Authority.
The current maintenance authority for the standard is the FGDC Secretariat. The Federal Geographic Data Committee is the approving authority for the standard. Questions concerning the standard are to be addressed to the FGDC Secretariat, in care of the U.S. Geological Survey, 590 National Center, Reston, Virginia 20192. Copies of this publication are available from the Federal Geographic Data Committee. Secretariat, in care of the U.S. Geological Survey, 590 National Center, Reston, Virginia 20192; telephone (703) 648-5514; facsimile (703) 648-5755; Internet (electronic mail) email@example.com. The text also is available at the FGDC web site http://www.fgdc.gov/metadata.