This definition is representation of the concept of a volumetric geological and geotechnical model, usually an interpretation but sometimes created direct from ground penetrating measurement. The contained subtypes of IfcGeotechnicalStratum have shape representations made from polyhedron or surfaces if a 'Yabuki' top surface model is used.

This IfcElement subtype is an anomaly in the sense that it does not have a PredefinedType attribute. This is to be provided in subsequent versions of the standard.