Geography Markup Language (GML)

Overview

Geography Markup Language (GML) is an XML-based format for encoding geographic information, allowing for the representation and exchange of spatial data in GIS applications. GML is an OGC standard and serves as the default output format for WFS.

Key Concepts

Feature is a geographic object with geometry and properties. Geometry uses GML-specific elements (Point, LineString, Polygon, etc.). Coordinate Reference System is specified via srsName attribute. Application schema defines domain-specific feature types. Profile is a subset of GML for specific use cases (Simple Features).

GML Structure

<gml:FeatureCollection>
  <gml:featureMember>
    <myns:Building gml:id="b1">
      <myns:name>City Hall</myns:name>
      <myns:geometry>
        <gml:Point srsName="EPSG:4326">
          <gml:pos>40.7128 -74.006</gml:pos>
        </gml:Point>
      </myns:geometry>
    </myns:Building>
  </gml:featureMember>
</gml:FeatureCollection>

Appendix

Created: 2025-12-13 | Modified: 2025-12-13

See Also

• Web Feature Service (WFS)
• Open Geospatial Consortium (OGC)
• GeoJSON
• Keyhole Markup Language (KML)

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