ST_AsGML — Return the geometry as a GML version 2 or 3 element.
text ST_AsGML(geometry  g1);
text ST_AsGML(geography  g1);
text ST_AsGML(geometry  g1, integer  precision);
text ST_AsGML(geography  g1, integer  precision);
text ST_AsGML(integer  version, geometry  g1);
text ST_AsGML(integer  version, geography  g1);
text ST_AsGML(integer  version, geometry  g1, integer  precision);
text ST_AsGML(integer  version, geography  g1, integer  precision);
text ST_AsGML(integer  version, geometry  g1, integer  precision, integer  options);
text ST_AsGML(integer  version, geography  g1, integer  precision, integer  options);
Return the geometry as a Geography Markup Language (GML) element. The version parameter, if specified, may be either 2 or 3. If no version parameter is specified then the default is assumed to be 2. The third argument may be used to reduce the maximum number of decimal places used in output (defaults to 15).
GML 2 refer to 2.1.2 version, GML 3 to 3.1.1 version
The last 'options' argument is a bitfield. It could be used to define CRS output type in GML output, and to declare data as lat/lon:
0: GML Short CRS (e.g EPSG:4326), default value
1: GML Long CRS (e.g urn:ogc:def:crs:EPSG::4326)
16: Declare that datas are lat/lon (e.g srid=4326). Default is to assume that data are planars. This option is usefull for GML 3.1.1 output only, related to axis order.
| ![[Note]](images/note.png) | |
| Availability: 1.3.2 Availability: 1.5.0 geography support was introduced. | 
 This function supports 3d and will not drop the z-index.
 This function supports 3d and will not drop the z-index.
SELECT ST_AsGML(ST_GeomFromText('POLYGON((0 0,0 1,1 1,1 0,0 0))',4326));
		st_asgml
		--------
		<gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>0,0 0,1 1,1 1,0 0,0</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon>
			SELECT ST_AsGML(3, ST_GeomFromText('POINT(5.234234233242 6.34534534534)',4326), 5, 17);
			st_asgml
			--------
		<gml:Point srsName="urn:ogc:def:crs:EPSG::4326"><gml:pos>6.34535 5.23423</gml:pos></gml:Point>