Geography Markup Language (GML)
The Geography Markup Language (GML) is an XML encoding for the transport and storage of geographic information, including both the geometry and properties of geographic features.
Penn State Dept. of Geography has an excellent online introductory GML course here.
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GML 3.2.1 (Approved July 2007)GML 3.1.1
GML 2.1.2 (deprecated)
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Profiles and Application schemaGML is a large, rich, expressive language designed to have the ability to express any geographic concept in common usage. Therefore, unless you are developing a universal, comprehensive GML parsing application, the proper way to use GML is probably not to learn the entire encoding specification right away, but to start with an application schema, or profile of GML. As explained here, "Profiles live in the GML namespaces (http://www.opengis.org/gml) and define restricted subsets of GML. Application schemas are XML vocabularies defined using GML and which live in an application-defined target namespace. Application schemas can be built on specific GML profiles or use the full GML schema set." Basically, profiles and application schemas are smaller subsets of the GML schema designed by a specific information community and tailored to a small number of uses. Status of GML 3.2.1 and ISO 19136 ISO 19136 (GML 3.2.1) has been published as an International Standard. GML 3.2.1 was approved as an OGC standard by the members on July 27, 2007. There is an associated document that contains the revision notes: changes from 3.1.1 to 3.2.1. Current GML Work There is a GML 3.3/4.0 Standards Working Group (SWG). For the past 4 months, this group has been collecting formal Change Requests. A public call for CRs closed just last week. The SWG will collect all of the CRs and begin discussions on the next revision to GML. GML Application Schemas and Profiles The pages listed below describe existing and emerging GML profile efforts from various user communities. Look on the references page for guidance on developing your own GML profile, and feel free to use this site as a workspace for your development. Web pages and discussion forums are available for your use. |
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