Appendix C: Geography Markup Language (GML)

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Scope

The Geography Markup Language (GML) is an XML encoding for the modelling, transport and storage of geographic information including both the spatial and non-spatial properties of geographic features. This specification defines the XML Schema syntax, mechanisms, and conventions that:

• Provide an open, vendor-neutral framework for the definition of geospatial application schemas and objects;
• Allow profiles that support proper subsets of GML framework descriptive capabilities;
• Support the description of geospatial application schemas for specialized domains and information communities;
• Enable the creation and maintenance of linked geographic application schemas and datasets;
• Support the storage and transport of application schemas and datasets;
• Increase the ability of organizations to share geographic application schemas and the information they describe.

United States Census Bureau Partnership - TIGER/GML

Statistics Canada has committed to working with the United States Census Bureau to ensure cross-border consistency in our products, and foster the development and application of a common, North American data model.

Like the United Kingdom Ordnance Survey and the United States Census Bureau, Statistics Canada has chosen to disseminate data in the Open Geospatial Consortium standard Geography Markup Language (GML) format. This standard allows organisations to achieve maximum compatibility not only of format but eventually of content. In partnership with the United States Census Bureau, Statistics Canada is committed to providing a harmonized North American street network file by 2008. This release of the Digital Boundary Files and Digital Cartographic Files, along with the Road Network File is the first step in delivering a harmonized international street network by 2008.

Example of 2006 Digital Boundary File dataset in GML format

<?xml version="1.0" encoding="ISO-8859-1"?>

<wfs:FeatureCollection 



          xmlns:c2006="http://geodepot.statcan.ca/2006"

                       xmlns:ogc="http://www.opengis.net/ogc"

                       xmlns:gml="http://www.opengis.net/gml"

                       xmlns:wfs="http://www.opengis.net/wfs"

                       xmlns:xlink="http://www.w3.org/1999/xlink"

                       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

                       xmlns="http://geodepot.statcan.ca/2006">

<gml:boundedBy>

<gml:Box srsName="">

         	<gml:coordinates>

-141.0180731504476,59.99999992446111 

-123.78932479367023,69.68942753358266

</gml:coordinates>

      </gml:Box>

   </gml:boundedBy>

   <gml:featureMember>

      <CensusSubdivision fid="C2006_CN_6001003">

         <csdUid>6001003</csdUid>

         <csdname>Watson Lake</csdname>

         <csdtype>T</csdtype>

         <prUid>60</prUid>

         <prname>Yukon Territory / Territoire du Yukon</prname>

         <cdUid>6001</cdUid>

         <cdname>Yukon</cdname>

         <cdtype>TER</cdtype>

         <cmacaUid/>

         <sactype>8</sactype>

         <erUid>6010</erUid>

         <ername>Yukon Territory / Territoire du Yukon</ername>

         <officialLimit>

            <gml:MultiPolygon srsName="EPSG:4269">

               <gml:polygonMember>

                  <gml:Polygon>

                     <gml:outerBoundaryIs>

                        <gml:LinearRing>

                           <gml:coordinates decimal="." cs="," ts=" ">

-128.72455401633565,60.070186461318286 

-128.7233706592442,60.06362661624902 

      			...

-128.7246792419692,60.070880147625736 

-128.72455401633565,60.070186461318286 

    </gml:coordinates>

                        </gml:LinearRing>

                     </gml:outerBoundaryIs>

                  </gml:Polygon>

               </gml:polygonMember>

            </gml:MultiPolygon>

         </officialLimit>

      </CensusSubdivision>

   </gml:featureMember>

   <gml:featureMember>

      <CensusSubdivision fid="C2006_CN_6001004">

         <csdUid>6001004</csdUid>

<csdname>Faro</csdname>

		... etc ....

      </CensusSubdivision>

   </gml:featureMember>

</wfs:FeatureCollection>