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A voiding feature is a modification of an element which reduces its volume. Such a feature may be manufactured in different ways, for example by cutting, drilling, or milling of members made of various materials, or by inlays into the formwork of cast members made of materials such as concrete.

The standard use of instances of IfcVoidingFeature is as a part of element type objects (instances of subtypes of IfcElementType). The part–whole relationship is established by an aggregation relationship object, expressing the decomposition of an element type into one or more additive elements (element parts) and zero or more feature elements.

HISTORY  New entity in IFC4.

Containment Use Definition

Voiding features shall have no spatial containment relationship to the spatial structure since they are dependent on element types without spatial containment relationships or on an element occurrence with own spatial containment relationship.

Common Use Definitions

The following concepts are inherited at supertypes:

 Instance diagram

Property Sets for Objects

The Property Sets for Objects concept applies to this entity as shown in Table 677.

Table 677 — IfcVoidingFeature Property Sets for Objects

Product Placement

The Product Placement concept applies to this entity as shown in Table 678.
IfcLocalPlacementIfcLocalPlacementRelative placement according to position and rotation relative to container.
IfcLocalPlacement Absolute placement according to position and rotation of world coordinate system.
IfcGridPlacement Placement according to grid intersection.

Table 678 — IfcVoidingFeature Product Placement

The local placement for IfcVoidingFeatureElement is defined in its supertype IfcProduct. It is defined by the IfcLocalPlacement, which defines the local coordinate system that is referenced by all geometric representations.

Profile Geometry

The Profile Geometry concept applies to this entity as shown in Table 679.
   Symbolic representations may be used for simple shapes such as holes or edge features.

Table 679 — IfcVoidingFeature Profile Geometry

Surface Geometry

The Surface Geometry concept applies to this entity as shown in Table 680.

Table 680 — IfcVoidingFeature Surface Geometry

Body Geometry

The Body Geometry concept applies to this entity as shown in Table 681.
   Volumetric representations may be used to semi-parametrically model the actual volume of the void created by the feature. Attributes in the shape model directly correspond with feature parameters, for example diameter of circular holes or length and width of cutouts. The objects within the shape model of the feature's shape representation can be included into a CSG model within a representation map of the parent element type.

Table 681 — IfcVoidingFeature Body Geometry

XSD Specification:

 <xs:element name="IfcVoidingFeature" type="ifc:IfcVoidingFeature" substitutionGroup="ifc:IfcFeatureElementSubtraction" nillable="true"/>
 <xs:complexType name="IfcVoidingFeature">
   <xs:extension base="ifc:IfcFeatureElementSubtraction">
    <xs:attribute name="PredefinedType" type="ifc:IfcVoidingFeatureTypeEnum" use="optional"/>

EXPRESS Specification:

ENTITY IfcVoidingFeature
SUBTYPE OF IfcFeatureElementSubtraction;
PredefinedType : OPTIONAL IfcVoidingFeatureTypeEnum;
HasObjectType : NOT EXISTS(PredefinedType) OR (PredefinedType <> IfcVoidingFeatureTypeEnum.USERDEFINED) OR EXISTS(SELF\IfcObject.ObjectType);

Link to EXPRESS-G diagram EXPRESS-G diagram

Attribute Definitions:

PredefinedType : Qualifies the feature regarding its shape and configuration relative to the voided element.

Formal Propositions:

HasObjectType : The attribute ObjectType shall be given if the predefined type is set to USERDEFINED.

Inheritance Graph:

ENTITY IfcVoidingFeature
GlobalId : IfcGloballyUniqueId;
OwnerHistory : OPTIONAL IfcOwnerHistory;
Name : OPTIONAL IfcLabel;
Description : OPTIONAL IfcText;
ENTITY IfcObjectDefinition
HasAssignments : SET OF IfcRelAssigns FOR RelatedObjects;
Nests : SET [0:1] OF IfcRelNests FOR RelatedObjects;
IsNestedBy : SET OF IfcRelNests FOR RelatingObject;
HasContext : SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions;
IsDecomposedBy : SET OF IfcRelAggregates FOR RelatingObject;
Decomposes : SET [0:1] OF IfcRelAggregates FOR RelatedObjects;
HasAssociations : SET OF IfcRelAssociates FOR RelatedObjects;
ENTITY IfcObject
ObjectType : OPTIONAL IfcLabel;
IsDeclaredBy : SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects;
Declares : SET OF IfcRelDefinesByObject FOR RelatingObject;
IsTypedBy : SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects;
IsDefinedBy : SET OF IfcRelDefinesByProperties FOR RelatedObjects;
ENTITY IfcProduct
ObjectPlacement : OPTIONAL IfcObjectPlacement;
Representation : OPTIONAL IfcProductRepresentation;
ReferencedBy : SET OF IfcRelAssignsToProduct FOR RelatingProduct;
ENTITY IfcElement
Tag : OPTIONAL IfcIdentifier;
FillsVoids : SET [0:1] OF IfcRelFillsElement FOR RelatedBuildingElement;
ConnectedTo : SET OF IfcRelConnectsElements FOR RelatingElement;
IsInterferedByElements : SET OF IfcRelInterferesElements FOR RelatedElement;
InterferesElements : SET OF IfcRelInterferesElements FOR RelatingElement;
HasProjections : SET OF IfcRelProjectsElement FOR RelatingElement;
ReferencedInStructures : SET OF IfcRelReferencedInSpatialStructure FOR RelatedElements;
HasOpenings : SET OF IfcRelVoidsElement FOR RelatingBuildingElement;
IsConnectionRealization : SET OF IfcRelConnectsWithRealizingElements FOR RealizingElements;
ProvidesBoundaries : SET OF IfcRelSpaceBoundary FOR RelatedBuildingElement;
ConnectedFrom : SET OF IfcRelConnectsElements FOR RelatedElement;
ContainedInStructure : SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements;
ENTITY IfcFeatureElement
ENTITY IfcFeatureElementSubtraction
VoidsElements : IfcRelVoidsElement FOR RelatedOpeningElement;
ENTITY IfcVoidingFeature
PredefinedType : OPTIONAL IfcVoidingFeatureTypeEnum;

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