Gazetteer (Flat Vocabulary)

In the context of metadataData about data. Metadata provides a context for research findings, ideally in a machine-readable format. It enables discovery of data via an electronic interface, and correct use and attribution of findings. Related Guide, a gazetteer is a geographic term list, which is a specific type of flat controlled vocabularyA managed list of terms. In the context of vocabularies, management typically includes careful selection of terms, maintenance of terms over time (i.e. addition, deprecation, modification), and presentation of the vocabulary in an accessible format. Related Guide.

Discussion

The main point of a gazetteer is to identify locations within a standardized coordinate system. For systems to be able to communicate effectively, locations must be clearly articulated.

The additional information provided by a gazetteer includes the necessary points of reference to find that particular location. These points of reference take the form of coordinates (lat/lon, x/y, etc.); the coordinates themselves come from a taxonomy that provides coordinates for a list of pre-defined locations. (TaxonomiesA multi-level controlled vocabulary in which metadata terms are grouped according to subject-specific classes, usually hierarchical. Related Guide are discussed in the Multi-Level VocabulariesA managed list of metadata terms, where the terms are organized into categories. Multi-Level vocabularies include taxonomies and subject headings. Related Guide section.)

In a global environment this is very important. If a project divides the globe into a set of very specific regions, the gazetteer provides reference points and, therefore, meaning to the names for these regions. By necessity, a gazetteer will encompass a GISGeographic Information System (geographic information system). It can take the form of an XMLeXtensible Markup Language file, an ArcGIS layer, a shapefile, or a location information file designed for a home-grown interface.

Example - National Geospatial Intelligence Agency Country Files

Click on image to enlarge.

This gazetteer (represented in a table for web display purposes) is available online. Each area is completely described in one row of the document. Documentation provided by the managing body is extremely important. Without it, you might be able to guess that LAT is latitude in decimal degrees, but you might not understand that DMS_LAT is latitude in degrees, minutes, and seconds. In addition, codes used throughout this gazetteer indicate things like a region or a feature classification. Neither the gazetteer nor the code list would make sense alone.