The Geography Markup Language (GML) is the XML grammar defined by the Open Geospatial Consortium (OGC) to express geographical features.

Key to GML's utility is its ability to integrate all forms of geographic information, including not only conventional "vector" or discrete objects, but coverages (see also GMLJP2) and sensor data.

These primitives include: The original GML model was based on the World Wide Web Consortium's Resource Description Framework (RDF).

Application schemas are XML vocabularies defined using GML and which live in an application-defined target namespace.

contains a pair of XSLT scripts (usually referred to as the "subset tool") that can be used to construct GML profiles.

Listing the elements and attributes to include in the resultant profile schema and running the tool results in a single profile schema file containing only the user-specified items and all of the element, attribute and type declarations on which the specified items depend.

Some Profile schemas created in this manner support other specifications including IHO S-57 and GML in JPEG 2000.

Over 90% of GML's structures (such as, to name a few, metadata, coordinate reference systems, horizontal and vertical datums, geometric integrity of circles, ellipses, arcs, etc.)

Lake presented his early ideas to an OGC meeting in Atlanta, Georgia, in February 1999, under the title xGML.

This introduced the idea of a GeoDOM, and the notion of Geographic Styling Language (GSL) based on XSL.

This led to the creation of SFXML (Simple Features XML) with input from Galdos, US Census, and NTT Data.

The paper also proposed that the language be based on the Resource Description Framework (RDF) rather than on the DTDs used to that point.

[14] Even before the passage of the Recommendation Paper at the OGC, Galdos had started work on an XML Schema version of GML, replacing the rdf:resource scheme for remote references with the use of xlink:href, and developing specific patterns (e.g. Barbarians at the Gate) for handling extensions for complex structures like feature collections.

Other important inputs in this time frame came from Simon Cox (CSIRO Australia), Paul Daisey (US Census), David Burggraf (Galdos), and Adrian Cuthbert (Laser-Scan).

The US Army Corps of Engineers sponsored the “USL Pilot” project, which was very helpful in exploring the utility of linking and styling concepts in the GML specification, with important work being done by Monie (Ionic) and Xia Li (Galdos).

The XML Schema specification draft was submitted by Galdos and was approved for public distribution in December 2000.

As these events were unfolding, work was continuing in parallel in Japan on G-XML under the auspices of the Japanese Database Promotion Center under the direction of Mr. Shige Kawano.

Mover, POI), while GML provided a very limited concrete set and built more complex objects by the use of application schemas.

On the one hand G-XML required the use of many fundamental constructs not at the time in the GML lexicon, including temporality, spatial references by identifiers, objects having histories, and the concept of topology-based styling.

A set of meetings held in Tokyo in January 2001, and involving Ron Lake (Galdos), Richard Martell (Galdos), OGC Staff (Kurt Buehler, David Schell), Mr. Shige Kawano (DPC), Mr. Akifumi Nakai (NTT Data) and Dr. Shimada (Hitachi CRL) led to the signing of an MOU between DPC and OGC by which OGC would endeavour to inject the fundamental elements required to support G-XML into GML, thus enabling G-XML to be written as a GML application schema.

This laid the foundation for GML 3, although a significant new development occurred in this time frame, namely the intersection of the OGC and ISO/TC 211.

On June 12, 2002, Mr. Ron Lake was recognized by the OGC for his work in creating GML by being presented the Gardels award.

[15] The citation on the award reads “In particular, this award recognizes your great achievement in creating the Geography Markup Language, (GML), and your uniquely sensitive and effective work to promote the reconciliation of national differences to promote meaningful standardization of GML on a global level.” Simon Cox (CSIRO)[16] and Clemens Portele (Interactive Instruments)[17] also subsequently received the Gardels award, in part for their contributions to GML.

GML can[clarification needed] also be included in version 2.1 of the United States National Information Exchange Model (NIEM).

It resulted from unification of the Open Geospatial Consortium definitions and Geography Markup Language (GML) with the ISO-191xx standards.