A HarnessGeometrySpecification3D represents either a 3D-model in the car coordinate system or a 3D-model in the formboard system. Each HarnessGeometrySpecification3D is a container for various instances of the class BuildingBlockPositioning3D. Each BuildingBlockPositioning3D determines the positioning of a specific BuildingBlockSpecification3D in the context of the HarnessGeometrySpecification3D by referencing a BuildingBlockSpecification3D and optionally specifying a Transformation3D for the case that a coordinate transformation is required.

A BuildingBlockSpecification3D represents a specific geometrical subset normally belonging to a certain Zone. Each BuildingBlockSpecification3D is a container for various instances of the classes GeometryNode3D, GeometrySegment3D, CartesianPoint3D and OccurrenceOrUsageViewItem3D.

Each GeometryNode3D references a CartesianPoint3D which determines its position within the BuildingBlockSpecification3D. Moreover, it can specify which TopologyNode it represents.

Each GeometrySegment3D can specify an ordered set of Curves in order to approximate its geometry (explained in detail on the next diagram). Moreover, it can specify which TopologySegment it represents.

Note: The data model does not constrain a GeometryNode3D respectively a GeometrySegment3D to reference a TopologyNode respectively a TopologySegment. This allows a VEC e.g. to transport 3D-information independently from a TopologySpecification. However, for the description of dimensions including tolerances as well as segment cross-section-areas and placements especially OnWayPlacements the VEC requires adequate references to the relevant elements in the topology.

Each OccurrenceOrUsageViewItem3D can reference which OccurrenceOrUsages it represents. Furthermore, it can specify a Transformation3D which determines its position and orientation of the component's 3D model within the space of the BuildingBlockSpecification3D. If no Transformation3D is defined, the OccurrenceOrUsageViewItem3D is meant to be placed implicitly by its position in the topology (e.g. wire protections with an OnWayPlacement.