<complexType name="TriangleType">
	<annotation>
		<documentation>Represents a triangle as a surface with an outer boundary consisting of a linear ring. Note that this is a polygon (subtype) with no inner boundaries. The number of points in the linear ring must be four.</documentation>
	</annotation>
	<complexContent>
		<extension base="gml:AbstractSurfacePatchType">
			<sequence>
				<element ref="gml:exterior">
					<annotation>
						<documentation>Constraint: The Ring shall be a LinearRing and must form a triangle, the first and the last position must be co-incident.</documentation>
					</annotation>
				</element>
			</sequence>
			<attribute name="interpolation" type="gml:SurfaceInterpolationType" fixed="planar">
				<annotation>
					<documentation>The attribute "interpolation" specifies the interpolation mechanism used for this surface patch. Currently only planar surface patches are defined in GML 3, the attribute is fixed to "planar", i.e. the interpolation method shall return points on a single plane. The boundary of the patch shall be contained within that plane.</documentation>
				</annotation>
			</attribute>
		</extension>
	</complexContent>
</complexType>