IfcPhysicalSimpleQuantity

物理量IfcPhysicalSimpleQuantity是一个实体，它包含单个量度量值（在IfcPhysicalSimpleQuantity的子类型中定义）以及度量值用法的语义定义。

例如，一个图元（如墙）可能具有多个面积度量，如迹线面积、左墙面面积、右墙面面积。这些区域将由具有不同名称字符串值的区域数量子类型的三个实例给出。

作为IfcBuildingElement的子类型的单个实体的“数量使用定义”一节为使用Name属性来描述单个数量提供了指导。如果给定了Unit属性，则value属性（在IfcPhysicalSimpleQuantity的子类型级别引入）将作为该单位的数量给定，否则将使用全局单位定义（由IfcUnitAssignment给定）。

IFC2x2附录1中增加的新实体。

IFC2x2附录1增加了抽象实体IfcPhysicalSimpleQuantity。保证了基于文件的交换的向上兼容性。

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
IfcPhysicalQuantity
1	Name	IfcLabel	[1:1]	Name of the element quantity or measure. The name attribute has to be made recognizable by further agreements.	X
2	Description	IfcText	[0:1]	Further explanation that might be given to the quantity.	X
	HasExternalReferences	IfcExternalReferenceRelationship @RelatedResourceObjects	S[0:?]	Reference to an external reference, e.g. library, classification, or document information, that is associated to the quantity.	X
	PartOfComplex	IfcPhysicalComplexQuantity @HasQuantities	S[0:1]	Reference to a physical complex quantity in which the physical quantity may be contained.	X
IfcPhysicalSimpleQuantity
3	Unit	IfcNamedUnit	[0:1]	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.	X

 

EXPRESS Specification

ENTITY IfcPhysicalSimpleQuantity
 ABSTRACT SUPERTYPE OF(ONEOF(IfcQuantityArea, IfcQuantityCount, IfcQuantityLength, IfcQuantityTime, IfcQuantityVolume, IfcQuantityWeight))
 SUBTYPE OF (IfcPhysicalQuantity);
  Unit : OPTIONAL IfcNamedUnit;
END_ENTITY;