This parameter specifies whether IFC objects should be read in a relational or hierarchical manner. Because the value of this parameter affects the reader schema, this parameter can only be set when an IFC reader is added to a workspace.
By default, the IFC reader operates in relational mode. When operating in relational mode, the IFC reader will produce a feature for each object in the IFC file. It is possible to re-create the object hierarchy using attribute values. For example, the ifc_parent_id attribute will contain the same value as the GlobalId value of the object's parent.
Note: The value of this parameter affects the reader schema: to change the Data Model parameter after workspace creation, you must remove the existing IFC reader and add a new reader.
When operating in hierarchical mode, the IFC reader will produce a single IfcProject feature. This feature will contain many levels of nested aggregate geometries, representing the hierarchy of objects in the source IFC file. For example, the project may contain an IFMEAggregate geometry representing an IfcSite object, which may in turn contain an IFMEAggregate representing an IfcBuilding object, and so on. Each IFC object can be identified by its geometry name. This single large feature can then be manipulated in FME Workbench, using transformers such as the GeometryPartRemover and/or the GeometryPartExtractor.