IfcRelVoidsElement

IfcRelVoidsElement是建筑元素和一个在元素中创建空白的打开元素之间的对象化关系。这是一对一的关系。这种关系意味着在元素的几何体和洞口之间进行布尔运算。
如图所示，将空隙插入墙中由ifcrelvoidelement关系表示。这个洞口是由IfcWall（StandardCase）o--IfcRelVoidsElement--o IfcOpeningElement在墙内创建的。

IFC1.0增加的新实体

#	Attribute	Type	Cardinality	Description	C
IfcRoot
1	GlobalId	IfcGloballyUniqueId	[1:1]	Assignment of a globally unique identifier within the entire software world.	X
2	OwnerHistory	IfcOwnerHistory	[0:1]	Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object, NOTE  only the last modification in stored - either as addition, deletion or modification.	X
3	Name	IfcLabel	[0:1]	Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule.	X
4	Description	IfcText	[0:1]	Optional description, provided for exchanging informative comments.	X
IfcRelationship
IfcRelDecomposes
IfcRelVoidsElement
5	RelatingBuildingElement	IfcElement	[1:1]	Reference to element in which a void is created by associated feature subtraction element.	X
6	RelatedOpeningElement	IfcFeatureElementSubtraction	[1:1]	Reference to the feature subtraction element which defines a void in the associated element.	X