The physical quantity, IfcPhysicalSimpleQuantity, is an entity that holds a single quantity measure value (as defined at the subtypes of IfcPhysicalSimpleQuantity) together with a semantic definition of the usage for the measure value.
EXAMPLE An element, like a wall, may have several area measures, like footprint area, left wall face area, right wall face area. These areas would be given by three instances of the area quantity subtype, with different Name string values.
A section "Quantity Use Definition" at individual entities as subtypes of IfcBuildingElement gives guidance to the usage of the Name attribute to characterize the individual quantities. If the Unit attribute is given, the value attribute (introduced at the level of subtypes of IfcPhysicalSimpleQuantity) are given as quantities of this unit, otherwise the global unit definitions (given by IfcUnitAssignment) are used.
HISTORY New entity in IFC2x2 Addendum 1.
IFC2x2 ADDENDUM 1 CHANGE The abstract entity IfcPhysicalSimpleQuantity has been added. Upward compatibility for file based exchange is guaranteed.
|1||Name||IfcLabel||Name of the element quantity or measure. The name attribute has to be made recognizable by further agreements.|
|2||Description||OPTIONAL IfcText||Further explanation that might be given to the quantity.|
|HasExternalReferences||SET [0:?] OF IfcExternalReferenceRelationship FOR RelatedResourceObjects||Reference to an external reference, e.g. library, classification, or document information, that is associated to the quantity.|
> IFC4 CHANGE New inverse attribute.
|PartOfComplex||SET [0:1] OF IfcPhysicalComplexQuantity FOR HasQuantities||Reference to a physical complex quantity in which the physical quantity may be contained.|
|3||Unit||OPTIONAL IfcNamedUnit||Optional assignment of a unit. If no unit is given, then the global unit assignment, as established at the IfcProject, applies to the quantity measures.|
ENTITY IfcPhysicalSimpleQuantity ABSTRACT SUPERTYPE OF (ONEOF (IfcQuantityArea ,IfcQuantityCount ,IfcQuantityLength ,IfcQuantityTime ,IfcQuantityVolume ,IfcQuantityWeight)) SUBTYPE OF (IfcPhysicalQuantity); Unit : OPTIONAL IfcNamedUnit; END_ENTITY;