IfcQuantityArea is a physical quantity that defines a derived area measure to provide an element's physical property. It is normally derived from the physical properties of the element under the specific measure rules given by a method of measurement.
EXAMPLE An opening may have an opening area used to deduct it from the wall surface area. The actual size of the area depends on the method of measurement used.
HISTORY New entity in IFC2x. It replaces the calcXxx attributes used in previous IFC Releases.
|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.|
|4||AreaValue||IfcAreaMeasure||Area measure value of this quantity.|
|5||Formula||OPTIONAL IfcLabel||A formula by which the quantity has been calculated. It can be assigned in addition to the actual value of the quantity. Formulas could be mathematic calculations (like width x height), database links, or a combination. The formula is for informational purposes only.|
> IFC4 CHANGE Attribute added to the end of the attribute list.
ENTITY IfcQuantityArea SUBTYPE OF (IfcPhysicalSimpleQuantity); AreaValue : IfcAreaMeasure; Formula : OPTIONAL IfcLabel; WHERE WR21 : NOT(EXISTS(SELF\IfcPhysicalSimpleQuantity.Unit)) OR (SELF\IfcPhysicalSimpleQuantity.Unit.UnitType = IfcUnitEnum.AREAUNIT); WR22 : AreaValue >= 0.; END_ENTITY;