NE GIS Metadata Standards

Metadata Standards

Metadata is data about data. For geographic information, it provides fundamental knowledge concerning the characteristics and quality of geographic data and provides data documentation for indexing and quality assurance purposes. Metadata library ranges from simple indexing (general knowledge about where the data is located) to complex data dictionaries describing and defining various elements of a data set. Metadata consists of five broad components or categories: (1) lineage (sources, transformations, control, computational precision); (2) positional accuracy (location, coordinates, absolute and relative measures); (3) attribute accuracy (scale, size, compliance, sampling tests, multi-layer comparisons); (4) logical consistency (graphic, topology, test results); and (5) completeness (availability, accessibility, mapping rules used, compliance with standard geocodes, taxonomic and spatial exhaustiveness).

The most advanced standard developed so far is the Spatial Data Transfer Standard (SDTS). SDTS is the spatial data transfer standard of the Federal government and was developed by Federal Geographic Data Committee (FGDC) in cooperation with other federal agencies. The National Institute of Standards and Technology (NIST) adopted SDTS as a federal Information Processing Standard (FIPS 173). As part of the logical specifications for the standard, information is to be transferred which fully describes the data including the data quality of the spatial components and any associated attributes. This component of the transfer standard is referred to as the metadata. The review period for this standard ended in April 1993.

The metadata portion of SDTS can be broken down into several components, including:

• Identification Section - describes the general data content, spatial extent, and use of the data.
• Projection Information - describes the horizontal and vertical coordinate systems used for the spatial data.
• Data Custodian Information - provides points of contact for the data.
• Access Information - provides details about the means of and conditions for accessing the data.
• Status Information - describes the state of, maintenance cycles for, and policies on availability of data.
• Table Definitions Portions of the Data Dictionary/Scheme - describes the thematic content of features portrayed in the data.
• Table Attributes Portions of the Data Dictionary/Scheme - describes the thematic content of characteristics of the features portrayed in the data.
• Source Information - describes documents used to compile the data.
• Processing Steps - describes the procedures and parameters used to convert the source materials to the final data.
• Data Quality - describes the quality of the data to assist potential users to determine if the data is suitable for an application.
• Metadata Reference Section - describes the currentness of and contacts for the metadata.

Other Metadata Standards

The GIS Steering Committee's Data Inventory Pilot Project team produced a set of metadata to be stored as part of the Nebraska GIS data directory project. The team used the SDTS as an example and its standard is essentially a subset of it.

Other metadata standards have been produced by other states. A few of them include:

• The Wisconsin Land Records Committee report on Land Records Classification and Standards
• Indiana's GIS Data Documentation and Clearinghouse Standard.
• Kansas Standards and Procedures for Database Development by the Kansas GIS
• Technology Management Program.

Essentially, metadata identifies a database availability, its location, and other related data information or characteristics attributed to a database. Metadata attributes enable a database to be shared more appropriately and effectively. Therefore, the metadata standards should include a minimum set of metadata attributes which contribute to data access, sharing and communications. This set of metadata information may vary from database to database, and would also change when the structure of a database is modified or updated. For example, the this information could include station name, latitude-longitude coordinates, township-range- section, county, NRD, river basin, hydrologic unit information where the measurement stations, collection or sampling points are located. Furthermore, the attributes could include station ID, scale, accuracy, control points, purpose, collection dates and methods and other related information about the database.

Recommendation:

Upon review of the metadata standards used in both the data inventory project and the Spatial Data Transfer Standards (SDTS), the GIS Steering Committee recommends the establishment of a minimum set of information (metadata attributes) to be included with a GIS database structure (coverage).