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Significance and Use
5.1 Put simply, metadata is “data about data” and typically describes the content, quality, lineage, organization, availability, and other characteristics of the data. Metadata is typically used to: (1) determine the availability of certain data (for example, through searches of a data catalog or clearinghouse); (2) determine the fitness of data for an intended use; (3) determine the means of accessing data; and (4) enhance data analysis and interpretation by better understanding the data collection and processing procedures.
5.2 The use of metadata among current implementations of archived data management systems is limited and is not uniform; in fact, this deficiency was the original impetus for this metadata standard. There are several possible reasons for the limited and inconsistent use of metadata: (1) the deployment of archived data management systems is still in the early stages since its formal inclusion in the National ITS Architecture in 1999; (2) to date, no formal metadata structure has been designated (the National ITS Architecture only refers to a generic “data catalog”); and (3) writing good documentation (that is, metadata) is typically the last and least enjoyed aspect of developing information systems.
5.3 The use of metadata among the spatial data community is widespread and relatively uniform, due mostly to Executive Order 12906 issued in 1994 which called for the creation of a National Spatial Data Infrastructure (NSDI). This Executive Order mandated the creation of metadata standards, which were to be developed and maintained by the FGDC, a 19-member interagency committee. The spatial data community operates several metadata clearinghouses that, in effect, serve as virtual card catalogs to vast collections of online spatial data. Federal, State, and local agencies have adopted the FGDC metadata standard and use it to document available datasets. Significant resources from numerous agencies have been placed into the development of the NSDI and supporting elements like the FGDC metadata standard. Notwithstanding these significant resources, the adoption and implementation of the FGDC metadata standard by other agencies and entities in the past 8 to 10 years has been remarkable.
5.4 The 10-year vision for metadata implementation in archived data management systems should resemble (at a minimum) the current state of metadata implementation in the spatial data community. This vision for ADMS metadata includes the following: (1) a consortium of agencies that develop and maintain various metadata standards and supporting guidance; (2) metadata clearinghouses that advertise available data sets as well as fully support the operational concept of a virtual data warehouse as defined in the National ITS Architecture; and (3) widespread adoption and implementation of standardized ADMS metadata structures among public (Federal, State, and local) transportation agencies and private companies.
5.5 This metadata standard may be implemented in several ways. Some metadata producers may desire to implement metadata that can be easily read by humans, which would likely include many unrestricted free text entries. Other metadata producers may wish to implement metadata that is easily interpreted by computer systems. If automated computer interpretation of metadata is desired, more specificity may have to be applied to certain metadata elements to restrict domain values beyond free text.
5.6 The detail of this standard may appear intimidating, but the examples in the Appendix illustrate the relative simplicity of the standard when implemented. The existing FGDC standard offers the widespread availability of resources and tools to create, validate, and manage metadata (see http://www.fgdc.gov/metadata/links/metalinks.html). The implementation of this metadata standard in a basic information system should require minimal staff time and effort.
1.1 This standard practice describes a hierarchical outline of sections and elements to be used in developing metadata to support archived data management systems. Specifically, the standard establishes the names of metadata elements and compound elements to be used in the metadata, the definitions of these metadata elements and compound elements, and suggested information about and examples of the values that are to be provided for the metadata elements.
1.2 The metadata to be developed using this standard includes qualitative and quantitative data that is associated with an information system or information object for the purposes of description, administration, legal requirements, technical functionality, use and usage, and preservation. As such, it can be differentiated from other metadata in that it describes and provides an interpretation of an organized collection of data, not a single data element.
1.3 This standard is intended for use by those developing, managing, or maintaining an archived data management system. For example, public agencies can specify that this standard be used in the development of a metadata framework for data archives. Data collectors and data processing intermediaries may also use this standard to create metadata describing the original collection conditions and intermediate processing steps. The development of metadata by data collectors and data processing intermediaries can greatly assist in the development of comprehensive metadata by the data archive manager. The standard is intended for use by all levels of government and the private sector.
1.4 This standard is applicable to various types of operational data collected by intelligent transportation systems (ITS) and stored in an archived data management system. Similarly, the standard can also be used with other types of historical traffic and transportation data collected and stored in an archived data management system.
1.5 This standard does not specify the means by which metadata is to be organized in a computer system or in a data transfer, nor the means by which metadata is to be transmitted, communicated, or presented to the user. Additionally, the standard is not intended to reflect or imply a specific implementation design. An implementation design requires adapting the structure and form of the standard to meet specific application and environment requirements.
1.6 This standard adopts with minimal changes the Federal Geographic Data Committee’s (FGDC’s) existing Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998) as the recommended metadata framework for archived data management systems. The FGDC metadata standard was chosen as the framework because of its relevance and established reputation among the spatial data community. A benefit of using the FGDC standard is the widespread availability of informational resources and software tools to create, validate, and manage metadata (see http://www.fgdc.gov/metadata/links/metalinks.html). Commentary and several examples are provided in this standard to illustrate the use of the FGDC standard in the ITS domain. The detail of the standard may appear intimidating, but the examples in the Appendix illustrate the relative simplicity of the standard when implemented.
1.7 Users of this standard should note that several sections of the metadata standard (that is, Annex A3 and Annex A4) address spatial referencing documentation, which may not be applicable to all data archives. These spatial referencing sections are designated as mandatory-if-applicable, which means that metadata is not required for these sections if spatial referencing is not used. Annex A6, Distribution Information, is also designated as mandatory-if-applicable and thus may not be required.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
American National Standards Institute (ANSI) StandardsANSIINCITS61-1986(R2 Representation of Geographic Point Locations for Information Interchange (formerly ANSI X3.61-1986 (R1997), also formerly FIPS 70-1)
Federal Geographic Data Committee (FGDC) StandardFGDC-STD-001-1998 Content Standard for Digital Geospatial Metadata, Version 2.0
Federal Information Processing Standards (FIPS)FIPSPUB173-1(1994) Spatial Data Transfer Standard (STDS)
E867 Terminology Relating to Vehicle-Pavement Systems
E2259 Guide for Archiving and Retrieving Intelligent Transportation Systems-Generated Data
ICS Number Code 35.240.30 (IT applications in information, documentation and publishing)
UNSPSC Code 43211730(Data acquisition system)