Class of a Tunnel. Intended function of a Tunnel Actual usage of a Tunnel. Denotes the relation of an _AbstractTunnel to its parts. The gml:AssociationType attribute group for enabling the use of refs is not repeated in the restriction and thus omitted. The building part has to be given inline, i.e. explicitely in this property. The reason for this inline definition is that no BuildingPart is used by more than one building, thus the use or references to building parts defined elsewhere is prohibited. Denotes the relation of a Tunnel to its external installations. The gml:AssociationType attribute group for enabling the use of refs is not repeated in the restriction and thus omitted. The BuildingFurniture has to be given inline within this property, not by reference. An TunnelInstallation is an external part of a Tunnel which has a specific function or semantical meaning. As subclass of _CityObject, a TunnelInstallation inherits all attributes and relations, in particular an id, names, external references, generic attributes and generalization relations. Class of an tunnel installation. Function of a tunnel installation. Actual Usage of an tunnel installation. Denotes the relation of a Tunnel to its internal installations. The gml:AssociationType attribute group for enabling the use of refs is not repeated in the restriction and thus omitted. The BuildingFurniture has to be given inline within this property, not by reference. An IntTunnelInstallation is an interior part of a Tunnel which has a specific function or semantical meaning. Examples are interior stairs, railings, radiators or pipes. As subclass of _CityObject, an IntTunnelInstallation inherits all attributes and relations, in particular an id, names, external references, and generalization relations. Denotes the relation of an tunnel or hollow space to its bounding thematic surfaces (walls, roofs, ..). There is no differentiation between interior surfaces bounding hollow spaces and outer ones bounding tunnels (one reason is, that ClosureSurfaces belong to both types). It has to be made sure by additional integrity constraints that, e.g. a tunnel is not related to CeilingSurfaces or a room not to RoofSurfaces. A BoundarySurface (German translation is 'Begrenzungsfläche') is a thematic object which classifies surfaces bounding a building or a room. The geometry of a BoundarySurface is given by MultiSurfaces. As it is a subclass of _CityObject, it inherits all atributes and relations, in particular the external references, the generic attributes, and the generalization relations. Denotes the relation of an Building or Room to its bounding thematic surfaces (walls, roofs, ..). There is no differentiation between interior surfaces bounding rooms and outer ones bounding buildings (one reason is, that ClosureSurfaces belong to both types). It has to be made sure by additional integrity constraints that, e.g. a building is not related to CeilingSurfaces or a room not to RoofSurfaces. A BoundarySurface (German translation is 'Begrenzungsfläche') is a thematic object which classifies surfaces bounding a building or a room. The geometry of a BoundarySurface is given by MultiSurfaces. As it is a subclass of _CityObject, it inherits all atributes and relations, in particular the external references, the generic attributes, and the generalization relations. Denotes the relation of a hollow space to the furnitures it contains. Class of a Tunnel Furniture. Intended function of a Tunnel Furniture. Actual usage of a Tunnel Furniture. Denotes the relation of an _BondarySurface to its openings (doors, windows). The OpeningPropertyType element must either carry a reference to an _Opening object or contain an _Opening object inline, but neither both nor none. Type for openings (doors, windows) in walls. Used in LOD3 and LOD4 only. As subclass of _CityObject, an _Opening inherits all attributes and relations, in particular an id, names, external references, and generalization relations. Type for windows in walls. Used in LOD3 and LOD4 only . As subclass of _CityObject, a window inherits all attributes and relations, in particular an id, names, external references, and generalization relations. Type for doors in walls. Used in LOD3 and LOD4 only . As subclass of _CityObject, a Door inherits all attributes and relations, in particular an id, names, external references, and generalization relations.