Metadata, simply stated, is data about data. It is used to document the content, quality, format, ownership, and lineage of individual data sets. Perhaps the most familiar example of metadata is the "Nutrition Facts" panel printed on food and drink labels in the U.S.
Visit the Pennsylvania Spatial Data Access site. This is the website for the Pennsylvania Spatial Data Access (PASDA) geospatial data clearinghouse (built by Penn State). PASDA provides access to a wide array of spatial data for Pennsylvania as a whole and places within the state. Click on “Statewide Data” in the link under "Quick Links" at the bottom left of the page. You will see a list of many state-wide data sets. All can be downloaded (by clicking the disk icon) and are usable by multiple map services (lightning icon). Some have data viewers available (globe icon) and some can be added to a “cart” for mapping (plus icon). Click on a copy of the titles. You will see some basic metadata; what categories are included for all entries? Then, click on “View Full Metadata” to see an example of the kinds of detailed metadata that has been recorded. Users of the site can also download this metadata description as an XML file for later use.
Some metadata also provide the keywords needed to help users search for available data in larger specialized clearinghouses and in the World Wide Web. Going back to the PASDA site, look in the upper right; you will see a “Data Search” facility. Try a term such as “water”, “school”, or others that you might expect to see data for. If the term has been used in the database metadata, the data set will be listed.
In 1990, the U.S. Office of Management and Budget issued Circular A-16, which established the Federal Geographic Data Committee (FGDC) as the interagency coordinating body responsible for facilitating cooperation among federal agencies whose missions include producing and using geospatial data. FGDC is chaired by the Department of Interior, and is administered by United States Geological Survey (USGS).
In 1994, President Bill Clinton’s Executive Order 12906 charged the FGDC with coordinating the efforts of government agencies and private sector firms leading to a National Spatial Data Infrastructure (NSDI). The Order defined NSDI as "the technology, policies, standards and human resources necessary to acquire, process, store, distribute, and improve utilization of geospatial data" (White House, 1994). It called upon FGDC to establish a National Geospatial Data Clearinghouse, ordered federal agencies to make their geospatial data products available to the public through the Clearinghouse, and required them to document data in a standard format that facilitates Internet search. Agencies were required to produce and distribute data in compliance with standards established by FGDC. (The Departments of Defense and Energy were exempt from the order, as was the Central Intelligence Agency.)
Some of the key components included in the FGDC metadata standard include:
- identification information: who created the data, a brief description of its content, form, and purpose; its status, spatial extent, and use restrictions;
- data quality information: accuracy and completeness of attributes, horizontal and vertical positions, sources, and procedures used to create the data;
- spatial reference information: projection and/or coordinate system; datum and ellipsoid;
- entity and attribute information: feature and attribute categories used; and
- distribution information: availability, and how to acquire the data.
FGDC's Content Standard for Digital Geospatial Metadata is published at the FGDC standards publication site. Geospatial professionals understand the value of metadata, know how to find it, and how to interpret it.
Registered Penn State students should return now to the Chapter 4 folder in ANGEL (via the Resources menu to the left) to take a self-assessment quiz Metadata and Databases.
You may take practice quizzes as many times as you wish. They are not scored and do not affect your grade in any way.