In an IFC model, the project information (generated, for example, from an ARCHICAD project) is represented as a set of IFC Entities – such as elements, surfaces, and their relationships. Each IFC Entity (for example, an IfcWall) includes a fixed number of IFC Attributes, plus any number of additional IFC Properties. The IFC scheme encompasses several hundred entities, of which the building element-type entities (such as IfcWall and IfcColumn) represent only 25.
Some IFC Entities express characteristics of other entities. Some of these correspond to ARCHICAD attributes. These correspondences are mapped automatically when the IFC model is generated or exported, or when the IFC model is imported.
At IFC import, you can override the IfcPresentationLayerAssignment, the IfcMaterial and the IfcSurfaceStyleRendering entities with preset ARCHICAD Attributes.
This may lead to much cleaner project files, because the IFC model’s attribute set won’t be recreated if you do not want it.