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Definition from buildingSMART: A specialization of the general feature element, that represents an existence dependent elements which modify the shape and appearance of the associated master element. The IfcFeatureElementSubtraction offers the ability to handle shape modifiers as semantic objects within the IFC object model that subtract from the shape of the master element.

HISTORY: New entity in Release IFC2x Edition 2.
NOTE: The entity is introduced as an upward compatible extension of the IFC2x platform. It is an intermediate abstract supertype without defining its own explicit attributes. The existing IfcOpeningElement is subtyped from it.

Geometry Use Definitions

The geometric representation of IfcFeatureElementSubtraction is given by the IfcProductDefinitionShape, allowing multiple geometric representations.

Local Placement

The local placement for IfcFeatureElementSubtraction 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. The local placement is always defined in relation to the local placement of the building element from which the feature element substration is substracted:

Shape Representation

The geometry use definitions for the shape representation of the IfcFeatureElementSubtraction is given at the level of its subtypes.

EXPRESS specification:

ENTITY IfcFeatureElementSubtraction
SUBTYPE OF ( IfcFeatureElement);
VoidsElements  :  IfcRelVoidsElement FOR RelatedOpeningElement;

Attribute definitions:

VoidsElements  :  Reference to the Voids Relationship that uses this Opening Element to create a void within an Element. The Opening Element can only be used to create a single void within a single Element.

Inheritance graph

ENTITY IfcFeatureElementSubtraction;
GlobalId  :  IfcGloballyUniqueId;
OwnerHistory  :  IfcOwnerHistory;
Name  :  OPTIONAL IfcLabel;
Description  :  OPTIONAL IfcText;
ENTITY IfcObjectDefinition;
HasAssignments  :  SET OF IfcRelAssigns FOR RelatedObjects;
IsDecomposedBy  :  SET OF IfcRelDecomposes FOR RelatingObject;
Decomposes  :  SET [0:1] OF IfcRelDecomposes FOR RelatedObjects;
HasAssociations  :  SET OF IfcRelAssociates FOR RelatedObjects;
ENTITY IfcObject;
ObjectType  :  OPTIONAL IfcLabel;
IsDefinedBy  :  SET OF IfcRelDefines 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;
HasCoverings  :  SET OF IfcRelCoversBldgElements FOR RelatingBuildingElement;
HasProjections  :  SET OF IfcRelProjectsElement FOR RelatingElement;
HasStructuralMember  :  SET OF IfcRelConnectsStructuralElement FOR RelatingElement;
ReferencedInStructures  :  SET OF IfcRelReferencedInSpatialStructure FOR RelatedElements;
HasPorts  :  SET OF IfcRelConnectsPortToElement FOR RelatedElement;
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;