GML格式

GML (Geography Markup Language)

是OGC的XML标准，通过特征集合（FeatureCollection）来表示基本的地理要素

https://www.ogc.org/standards/gml

eg：

多边形

<Feature   fid="142" featureType="school" >
   <Description>Balmoral Middle School</Description>>
   <Property Name="NumFloors" type="Integer" value="3"/>
   <Property Name="NumStudents" type="Integer" value="987"/>
       <Polygon  name="extent" srsName="epsg:27354">
            <LineString  name="extent" srsName="epsg:27354">
                <CData>
                  491888.999999459,5458045.99963358 491904.999999458,5458044.99963358
                  491908.999999462,5458064.99963358 491924.999999461,5458064.99963358
                  491925.999999462,5458079.99963359 491977.999999466,5458120.9996336
                  491953.999999466,5458017.99963357 </CData>
        </LineString>
    </Polygon>
</Feature>