Type describing the features of the Digital Terrain Model. As subclass of _CityObject, a ReliefFeature inherits all attributes and relations, in particular an id, names, external references, and generalization relations. Type describing the components of a relief feature - either a TIN, a Grid, mass points or break lines. As subclass of _CityObject, a ReliefComponent inherits all attributes and relations, in particular an id, names, external references, and generalization relations. Denotes the relation of a ReliefFeature to its components. The ReliefComponentPropertyType element must either carry a reference to a _ReliefComponent object or contain a _ReliefComponent object inline, but neither both nor none. Type describing the TIN component of a relief feature. As subclass of _CityObject, a TINRelief inherits all attributes and relations, in particular an id, names, external references, and generalization relations. Type describing the raster component of a relief feature. As subclass of _CityObject, a RasterRelief inherits all attributes and relations, in particular an id, names, external references, and generalization relations. Type describing the mass point component of a relief feature. As subclass of _CityObject, a MassPoint Relief inherits all attributes and relations, in particular an id, names, external references, and generalization relations. Type describing the break line Component of a relief feature. A break line relief consists of break lines or ridgeOrValleyLines. As subclass of _CityObject, a BreaklineRelief inherits all attributes and relations, in particular an id, names, external references, and generalization relations. Denotes the relation of a TINRelief to its components. The tinPropertyType element must either carry a reference to a gml:TriangulatedSurface object or contain a gml:TriangulatedSurface object inline, but neither both nor none. Denotes the relation of a RasterReliefType to its components. The gridPropertyType element must either carry a reference to a gml:RectifiedGridCoverage object or contain a gml:RectifiedGridCoverage object inline, but neither both nor none.