Qto_VolumetricStratumBaseQuantities Quantity measures associated to volumetric stratum such as in a geotechnical model. Uncertainty is documented in _Pset_Uncertainty_. IfcGeotechnicalStratum IfcGeotechnicalStratum Area Calculated area for the object. Actual area of upper surface of shape. Q_AREA Mass Mass represented, if lower surface of stratum known. Q_WEIGHT PlanArea Projected plan area of upper surface of model. Q_AREA Volume Volume of the element. Volume represented, if lower surface of stratum known. Q_VOLUME