8.7.2.3 IfcQuantityArea

Quantité de surface
Mengenangabe - Fläche

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.

XSD Specification:

 <xs:element name="IfcQuantityArea" type="ifc:IfcQuantityArea" substitutionGroup="ifc:IfcPhysicalSimpleQuantity" nillable="true"/>
 <xs:complexType name="IfcQuantityArea">
  <xs:complexContent>
   <xs:extension base="ifc:IfcPhysicalSimpleQuantity">
    <xs:attribute name="AreaValue" type="ifc:IfcAreaMeasure" use="optional"/>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>

EXPRESS Specification:

ENTITY IfcQuantityArea
SUBTYPE OF (IfcPhysicalSimpleQuantity);
AreaValue : IfcAreaMeasure;
Formula : OPTIONAL IfcStrippedOptional;
WHERE
WR21 : NOT(EXISTS(SELF\IfcPhysicalSimpleQuantity.Unit)) OR (SELF\IfcPhysicalSimpleQuantity.Unit.UnitType = IfcUnitEnum.AREAUNIT);
WR22 : AreaValue >= 0.;
END_ENTITY;

Attribute Definitions:

AreaValue : Area measure value of this quantity.
Formula : 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.

Formal Propositions:

WR21 : If a unit is given, the unit type shall be area unit.
WR22 : A valid area quantity shall be greater than or equal to zero.

Inheritance Graph:

ENTITY IfcQuantityArea
ENTITY IfcPhysicalQuantity
Name : IfcLabel;
Description : OPTIONAL IfcStrippedOptional;
INVERSE
ENTITY IfcPhysicalSimpleQuantity
Unit : OPTIONAL IfcStrippedOptional;
ENTITY IfcQuantityArea
AreaValue : IfcAreaMeasure;
Formula : OPTIONAL IfcStrippedOptional;
END_ENTITY;

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