5.4.3.40 IfcOpeningElement

5.4.3.40.1 Semantic definition

The opening element stands for opening, recess or chase, all reflecting voids. It represents a void within any element that has physical manifestation. Openings can be inserted into walls, slabs, beams, columns, or other elements.

There are two different types of opening elements. The attribute PredefinedType should be used to capture the differences:

an opening, where the thickness of the opening is greater or equal to the thickness of the element — the attribute PredefinedType is set to OPENING
a recess or niche, where the thickness of the recess is smaller than the thickness of the element — the attribute PredefinedType is set to RECESS for a recess or niche.

If the value for PredefinedType is omitted, or the value is set to NOTDEFINED, no specific information of whether it is an opening or recess shall be assumed.

An IfcOpeningElement has to be inserted into an IfcElement by using the IfcRelVoidsElement relationship. It may be filled by an IfcDoor, IfcWindow, or another filling element by using the relationship IfcRelFillsElement. Depending on the type of the IfcShapeRepresentation of the IfcOpeningElement the voiding relationship implies:

if the IfcShapeRepresentation.RepresentationIdentifier = 'Body', then the Body shape representation of the opening has to be subtracted from the body shape representation of the voided element - implicit Boolean difference operation.
if the IfcShapeRepresentation.RepresentationIdentifier = 'Reference', then the Reference shape representation of the opening is not subtracted. It is provided in addition to the hole in the Body shape representation of the voided element.

The IfcOpeningElement shall not participate in the containment relationship, i.e. it is not linked directly to the spatial structure of the project. It has a mandatory VoidsElements inverse relationship pointing to the IfcElement that is contained in the spatial structure. The inverse relationship ContainedInStructure shall be NIL.

5.4.3.40.2 Entity inheritance

5.4.3.40.3 Attributes

#	Attribute	Type	Description
IfcRoot (4)
1	GlobalId	IfcGloballyUniqueId	Assignment of a globally unique identifier within the entire software world.
2	OwnerHistory	OPTIONAL IfcOwnerHistory	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 is stored - either as addition, deletion or modification. IFC4-CHANGE The attribute has been changed to be OPTIONAL.
3	Name	OPTIONAL IfcLabel	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.
4	Description	OPTIONAL IfcText	Optional description, provided for exchanging informative comments.
IfcObjectDefinition (7)
	HasAssignments	SET [0:?] OF IfcRelAssigns FOR RelatedObjects	Reference to the relationship objects, that assign (by an association relationship) other subtypes of IfcObject to this object instance. Examples are the association to products, processes, controls, resources or groups.
	Nests	SET [0:1] OF IfcRelNests FOR RelatedObjects	References to the decomposition relationship being a nesting. It determines that this object definition is a part within an ordered whole/part decomposition relationship. An object occurrence or type can only be part of a single decomposition (to allow hierarchical structures only). IFC4-CHANGE The inverse attribute datatype has been added and separated from Decomposes defined at IfcObjectDefinition.
	IsNestedBy	SET [0:?] OF IfcRelNests FOR RelatingObject	References to the decomposition relationship being a nesting. It determines that this object definition is the whole within an ordered whole/part decomposition relationship. An object or object type can be nested by several other objects (occurrences or types). IFC4-CHANGE The inverse attribute datatype has been added and separated from IsDecomposedBy defined at IfcObjectDefinition.
	HasContext	SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions	References to the context providing context information such as project unit or representation context. It should only be asserted for the uppermost non-spatial object. IFC4-CHANGE The inverse attribute datatype has been added.
	IsDecomposedBy	SET [0:?] OF IfcRelAggregates FOR RelatingObject	References to the decomposition relationship being an aggregation. It determines that this object definition is whole within an unordered whole/part decomposition relationship. An object definition can be aggregated by several other objects (occurrences or parts). IFC4-CHANGE The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates.
	Decomposes	SET [0:1] OF IfcRelAggregates FOR RelatedObjects	References to the decomposition relationship being an aggregation. It determines that this object definition is a part within an unordered whole/part decomposition relationship. An object definition can only be part of a single decomposition (to allow hierarchical structures only). IFC4-CHANGE The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates.
	HasAssociations	SET [0:?] OF IfcRelAssociates FOR RelatedObjects	Reference to the relationship objects, that associates external references or other resource definitions to the object. Examples are the association to library, documentation or classification.
IfcObject (5)
5	ObjectType	OPTIONAL IfcLabel	The type denotes a particular type that indicates the object further. The use has to be established at the level of instantiable subtypes. In particular it holds the user defined type, if the enumeration of the attribute PredefinedType is set to USERDEFINED or when the concrete entity instantiated does not have a PredefinedType attribute. The latter is the case in some exceptional leaf classes and when instantiating IfcBuiltElement directly.
	IsDeclaredBy	SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects	Link to the relationship object pointing to the declaring object that provides the object definitions for this object occurrence. The declaring object has to be part of an object type decomposition. The associated IfcObject, or its subtypes, contains the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes. IFC4-CHANGE New inverse relationship, change made with upward compatibility for file based exchange.
	Declares	SET [0:?] OF IfcRelDefinesByObject FOR RelatingObject	Link to the relationship object pointing to the reflected object(s) that receives the object definitions. The reflected object has to be part of an object occurrence decomposition. The associated IfcObject, or its subtypes, provides the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes. IFC4-CHANGE New inverse relationship, change made with upward compatibility for file based exchange.
	IsTypedBy	SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects	Set of relationships to the object type that provides the type definitions for this object occurrence. The then associated IfcTypeObject, or its subtypes, contains the specific information (or type, or style), that is common to all instances of IfcObject, or its subtypes, referring to the same type. IFC4-CHANGE New inverse relationship, the link to IfcRelDefinesByType was previously included in the inverse relationship IfcRelDefines. Change made with upward compatibility for file based exchange.
	IsDefinedBy	SET [0:?] OF IfcRelDefinesByProperties FOR RelatedObjects	Set of relationships to property set definitions attached to this object. Those statically or dynamically defined properties contain alphanumeric information content that further defines the object. IFC4-CHANGE The data type has been changed from IfcRelDefines to IfcRelDefinesByProperties with upward compatibility for file based exchange.
IfcProduct (5)
6	ObjectPlacement	OPTIONAL IfcObjectPlacement	This establishes the object coordinate system and placement of the product in space. The placement can either be absolute (relative to the world coordinate system), relative (relative to the object placement of another product), or constrained (e.g. relative to grid axes, or to a linear positioning element). The type of placement is determined by the various subtypes of IfcObjectPlacement. An object placement must be provided if a representation is present.
7	Representation	OPTIONAL IfcProductRepresentation	Reference to the representations of the product, being either a representation (IfcProductRepresentation) or as a special case of a shape representation (IfcProductDefinitionShape). The product definition shape provides for multiple geometric representations of the shape property of the object within the same object coordinate system, defined by the object placement.
	ReferencedBy	SET [0:?] OF IfcRelAssignsToProduct FOR RelatingProduct	Reference to the IfcRelAssignsToProduct relationship, by which other products, processes, controls, resources or actors (as subtypes of IfcObjectDefinition) can be related to this product.
	PositionedRelativeTo	SET [0:?] OF IfcRelPositions FOR RelatedProducts	Reference to the IfcRelPositions relationship, which defines its relationship with a positioning element.
	ReferencedInStructures	SET [0:?] OF IfcRelReferencedInSpatialStructure FOR RelatedElements	Reference to the objectified relationship IfcRelReferencedInSpatialStructure may be used to relate a product to one or more spatial structure elements in addition to the one in which it is primarily contained.
IfcElement (13)
8	Tag	OPTIONAL IfcIdentifier	The tag (or label) identifier at the particular instance of a product, e.g. the serial number, or the position number. It is the identifier at the occurrence level.
	FillsVoids	SET [0:1] OF IfcRelFillsElement FOR RelatedBuildingElement	Reference to the IfcRelFillsElement relationship that puts the element as a filling into the opening created within another element.
	ConnectedTo	SET [0:?] OF IfcRelConnectsElements FOR RelatingElement	Reference to the element connection relationship. The relationship then refers to the other element to which this element is connected to.
	IsInterferedByElements	SET [0:?] OF IfcRelInterferesElements FOR RelatedElement	Reference to the interference relationship to indicate the element that is interfered. The relationship, if provided, indicates that this element has an interference with one or many other elements. NOTE There is no indication of precedence between IsInterferedByElements and InterferesElements. IFC4-CHANGE New inverse relationship.
	InterferesElements	SET [0:?] OF IfcRelInterferesElements FOR RelatingElement	Reference to the interference relationship to indicate the element that interferes. The relationship, if provided, indicates that this element has an interference with one or many other elements. NOTE There is no indication of precedence between IsInterferedByElements and InterferesElements. IFC4-CHANGE New inverse relationship.
	HasProjections	SET [0:?] OF IfcRelProjectsElement FOR RelatingElement	Projection relationship that adds a feature (using a Boolean union) to the IfcBuiltElement.
	HasOpenings	SET [0:?] OF IfcRelVoidsElement FOR RelatingBuildingElement	Reference to the IfcRelVoidsElement relationship that creates an opening in an element. An element can incorporate zero-to-many openings. For each opening, that voids the element, a new relationship IfcRelVoidsElement is generated.
	IsConnectionRealization	SET [0:?] OF IfcRelConnectsWithRealizingElements FOR RealizingElements	Reference to the connection relationship with realizing element. The relationship, if provided, assigns this element as the realizing element to the connection, which provides the physical manifestation of the connection relationship.
	ProvidesBoundaries	SET [0:?] OF IfcRelSpaceBoundary FOR RelatedBuildingElement	Reference to space boundaries by virtue of the objectified relationship IfcRelSpaceBoundary. It defines the concept of an element bounding spaces.
	ConnectedFrom	SET [0:?] OF IfcRelConnectsElements FOR RelatedElement	Reference to the element connection relationship. The relationship then refers to the other element that is connected to this element.
	ContainedInStructure	SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements	Containment relationship to the spatial structure element, to which the element is primarily associated. This containment relationship has to be hierarchical, i.e. an element may only be assigned directly to zero or one spatial structure.
	HasCoverings	SET [0:?] OF IfcRelCoversBldgElements FOR RelatingBuildingElement	Reference to IfcCovering by virtue of the objectified relationship IfcRelCoversBldgElements. It defines the concept of an element having coverings associated.
	HasSurfaceFeatures	SET [0:?] OF IfcRelAdheresToElement FOR RelatingElement	Reference to the IfcRelAdheresToElement relationship that adheres a IfcSurfaceFeature to an element. An element can incorporate zero-to-many surface features in one relationship.
IfcFeatureElementSubtraction (1)
	VoidsElements	IfcRelVoidsElement FOR RelatedOpeningElement	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.
Click to show 35 hidden inherited attributes
IfcOpeningElement (2)
9	PredefinedType	OPTIONAL IfcOpeningElementTypeEnum	Predefined generic type for an opening that is specified in an enumeration. There may be a property set given specifically for the predefined types. IFC4-CHANGE The attribute has been added at the end of the entity definition.
	HasFillings	SET [0:?] OF IfcRelFillsElement FOR RelatingOpeningElement	Reference to the Filling Relationship that is used to assign Elements as Fillings for this Opening Element. The Opening Element can be filled with zero-to-many Elements.

Table 5.4.3.40.H

5.4.3.40.4 Formal propositions

Name Description

CorrectPredefinedType

Either PredefinedType is unset or the inherited attribute ObjectType shall be provided, if the PredefinedType is set to USERDEFINED.

 NOT(EXISTS(PredefinedType)) OR
 (PredefinedType <> IfcOpeningElementTypeEnum.USERDEFINED) OR
 ((PredefinedType = IfcOpeningElementTypeEnum.USERDEFINED) AND EXISTS (SELF\IfcObject.ObjectType))

Table 5.4.3.40.I

5.4.3.40.5 Property sets

Pset_Condition
- AssessmentDate
- AssessmentCondition
- AssessmentDescription
- AssessmentType
- AssessmentMethod
- LastAssessmentReport
- NextAssessmentDate
- AssessmentFrequency
Pset_ConstructionAdministration
- ProcurementMethod
- SpecificationSectionNumber
- SubmittalIdentifer
Pset_ConstructionOccurence
- InstallationDate
- ModelNumber
- TagNumber
- AssetIdentifier
Pset_ElementKinematics
- CyclicPath
- CyclicRange
- LinearPath
- LinearRange
- MaximumAngularVelocity
- MaximumConstantSpeed
- MinimumTime
Pset_EnvironmentalCondition
- ReferenceAirRelativeHumidity
- ReferenceEnvironmentTemperature
- MaximumAtmosphericPressure
- StorageTemperatureRange
- MaximumWindSpeed
- OperationalTemperatureRange
- MaximumRainIntensity
- SaltMistLevel
- SeismicResistance
- SmokeLevel
- MaximumSolarRadiation
Pset_EnvironmentalImpactIndicators
- Reference
- FunctionalUnitReference
- IndicatorsUnit
- LifeCyclePhase
- ExpectedServiceLife
- TotalPrimaryEnergyConsumptionPerUnit
- WaterConsumptionPerUnit
- HazardousWastePerUnit
- NonHazardousWastePerUnit
- ClimateChangePerUnit
- AtmosphericAcidificationPerUnit
- RenewableEnergyConsumptionPerUnit
- NonRenewableEnergyConsumptionPerUnit
- ResourceDepletionPerUnit
- InertWastePerUnit
- RadioactiveWastePerUnit
- StratosphericOzoneLayerDestructionPerUnit
- PhotochemicalOzoneFormationPerUnit
- EutrophicationPerUnit
Pset_EnvironmentalImpactValues
- TotalPrimaryEnergyConsumption
- WaterConsumption
- HazardousWaste
- NonHazardousWaste
- ClimateChange
- AtmosphericAcidification
- RenewableEnergyConsumption
- NonRenewableEnergyConsumption
- ResourceDepletion
- InertWaste
- RadioactiveWaste
- StratosphericOzoneLayerDestruction
- PhotochemicalOzoneFormation
- Eutrophication
- LeadInTime
- Duration
- LeadOutTime
Pset_InstallationOccurrence
- InstallationDate
- AcceptanceDate
- PutIntoOperationDate
Pset_MaintenanceStrategy
- AssetCriticality
- AssetFrailty
- AssetPriority
- MonitoringType
- AccidentResponse
Pset_MaintenanceTriggerCondition
- ConditionTargetPerformance
- ConditionMaintenanceLevel
- ConditionReplacementLevel
- ConditionDisposalLevel
Pset_MaintenanceTriggerDuration
- DurationTargetPerformance
- DurationMaintenanceLevel
- DurationReplacementLevel
- DurationDisposalLevel
Pset_MaintenanceTriggerPerformance
- TargetPerformance
- PerformanceMaintenanceLevel
- ReplacementLevel
- DisposalLevel
Pset_ManufacturerOccurrence
- AcquisitionDate
- BarCode
- SerialNumber
- BatchReference
- AssemblyPlace
- ManufacturingDate
Pset_ManufacturerTypeInformation
- GlobalTradeItemNumber
- ArticleNumber
- ModelReference
- ModelLabel
- Manufacturer
- ProductionYear
- AssemblyPlace
- OperationalDocument
- SafetyDocument
- PerformanceCertificate
Pset_OpeningElementCommon
- Reference
- Status
- Purpose
- FireExit
- FireRating
- AcousticRating
Pset_RepairOccurrence
- RepairContent
- RepairDate
- MeanTimeToRepair
Pset_Risk
- RiskName
- RiskType
- NatureOfRisk
- RiskAssessmentMethodology
- UnmitigatedRiskLikelihood
- UnmitigatedRiskConsequence
- UnmitigatedRiskSignificance
- MitigationPlanned
- MitigatedRiskLikelihood
- MitigatedRiskConsequence
- MitigatedRiskSignificance
- MitigationProposed
- AssociatedProduct
- AssociatedActivity
- AssociatedLocation
Pset_ServiceLife
- ServiceLifeDuration
- MeanTimeBetweenFailure
Pset_Tolerance
- ToleranceDescription
- ToleranceBasis
- OverallTolerance
- HorizontalTolerance
- OrthogonalTolerance
- VerticalTolerance
- PlanarFlatness
- HorizontalFlatness
- ElevationalFlatness
- SideFlatness
- OverallOrthogonality
- HorizontalOrthogonality
- OrthogonalOrthogonality
- VerticalOrthogonality
- OverallStraightness
- HorizontalStraightness
- OrthogonalStraightness
- VerticalStraightness
Pset_Uncertainty
- UncertaintyBasis
- UncertaintyDescription
- HorizontalUncertainty
- LinearUncertainty
- OrthogonalUncertainty
- VerticalUncertainty
Pset_Warranty
- WarrantyIdentifier
- WarrantyStartDate
- IsExtendedWarranty
- WarrantyPeriod
- WarrantyContent
- PointOfContact
- Exclusions
Qto_BodyGeometryValidation
- GrossSurfaceArea
- NetSurfaceArea
- GrossVolume
- NetVolume
- SurfaceGenusBeforeFeatures
- SurfaceGenusAfterFeatures
Qto_OpeningElementBaseQuantities
- Width
- Height
- Depth
- Area
- Volume

5.4.3.40.6 Concept usage

Brep representation — Figure 5.4.3.40.A — Building element body boundary representation

surface model — Figure 5.4.3.40.A — Building element body boundary representation

Concept	Usage	Description
IfcRoot (2)
Revision Control	General	Ownership, history, and merge state is captured using IfcOwnerHistory.
Software Identity	General	IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.
IfcObjectDefinition (9)
Classification Association	General	Any object occurrence or object type can have a reference to a specific classification reference, i.e. to a particular facet within a classification system.
Aggregation	General	No description available.
Approval Association	General	No description available.
Constraint Association	General	No description available.
Document Association	General	No description available.
Library Association	General	No description available.
Material Association	General	No description available.
Material Single	General	No description available.
Nesting	General	No description available.
IfcObject (5)
Object Predefined Type	General	No description available.
Object Typing	General	Any object occurrence can be typed by being assigned to a common object type utilizing this concept. A particular rule, restricting the applicable subtypes of IfcTypeObject that can be assigned, is introduced by overriding this concept at the level of subtypes of IfcObject. This concept can be applied to the following resources: IfcTypeObject
Object User Identity	General	An attribute Name and optionally Description can be used for all subypes of IfcObject. For those subtypes, that have an object type definition, such as IfcBeam - IfcBeamType, the common Name and optionally Description is associated with the object type.
Property Sets with Override	General	Any object occurrence can hold property sets, either directly at the object occurrence as element specific property sets, or at the object type, as type property sets. In this case, the properties that are provided to the object occurrence are the combinations of element specific and type properties. In case that the same property (within the same property set) is defined both in occurrence and type properties, the property value of the occurrence property overrides the property value of the type property.
Assignment to Group	General	No description available.
IfcProduct (18)
Body Geometry	General	The body or solid model geometric representation of an IfcProduct is typically defined using a Tessellation or Brep. Subtypes may provide recommendations on other representation types that may be used. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used: IfcShapeRepresentation.RepresentationIdentifier = 'Body' IfcShapeRepresentation.RepresentationType = Typically 'Tessellation' or 'Brep'
Product Geometric Representation	General	The geometric representation of any IfcProduct is provided by the IfcProductDefinitionShape allowing multiple geometric representations. It uses the Product Placement concept utilizing IfcLocalPlacement to establish an object coordinate system, in which all geometric representations are founded. NOTE A detailed specification of how to apply the local placement and which shape representations are applicable is provided at the level of subtypes of IfcProduct and is further determined by the model view definition and implementer agreements.
Product Geometry Colour	General	No description available.
Product Geometry Layer	General	No description available.
Product Relative Positioning	General	If the IfcProduct Product Placement is placed relative to an IfcPositioningElement this relationship covers the information on which IfcPositioningElement positions the IfcProduct.
Product Span Positioning	General	No description available.
Box Geometry	General	No description available.
CoG Geometry	General	No description available.
Mapped Geometry	General	No description available.
Object Typing	General	This is a further elaboration on an inherited concept. This concept can be applied to the following resources: IfcTypeProduct
Product Local Placement	General	No description available.
Product Topology Representation	General	No description available.
Property Sets for Objects	General	This concept can be applied to the following resources: Pset_Risk Pset_Tolerance Pset_Uncertainty
Quantity Sets	General	This concept can be applied to the following resources: Qto_BodyGeometryValidation
Reference Geometry	General	No description available.
Reference SweptSolid Geometry	General	No description available.
Reference SweptSolid PolyCurve Geometry	General	No description available.
Reference Tessellation Geometry	General	No description available.
IfcElement (44)
Body AdvancedBrep Geometry	General	An IfcElement (so far no further constraints are defined at the level of its subtypes or by view definitions) may be represented as a single or multiple boundary representation models, which include advanced surfaces, usually referred to as NURBS surfaces. The 'AdvancedBrep' representation allows for the representation of complex free-form element shape. NOTE View definitions or implementer agreements may restrict or disallow the use of 'AdvancedBrep' geometry.
Body AdvancedSwept Directrix Geometry	General	No description available.
Body AdvancedSwept DiskSolid PolyCurve Geometry	General	No description available.
Body AdvancedSwept Tapered Geometry	General	No description available.
Body Brep Geometry	General	Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple Boundary Representation models (which are restricted to be faceted Brep's with or without voids). The Brep representation allows for the representation of complex element shape. Figure 5.4.3.40.A — Building element body boundary representation EXAMPLE As shown in Figure 5.4.3.40.A, the Brep representation is given by an IfcShapeRepresentation, which includes one or more items, all of type IfcFacetedBrep. In some cases it may be useful to also expose a simple representation as a bounding box representation of the same complex shape.
Body CSG Geometry	General	Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a CSG primitive or CSG tree. The CSG representation allows for the representation of complex element shape. NOTE View definitions or implementer agreements may restrict or disallow the use of 'CSG' geometry.
Body SectionedSolidHorizontal	General	No description available.
Body SurfaceModel Geometry	General	Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple surface models, based on either shell or face based surface models. It may also include tessellated models. Figure 5.4.3.40.B — Element surface model representation EXAMPLE As shown in Figure 5.4.3.40.B, the surface model representation is given by an IfcShapeRepresentation, which includes a single item which is either an IfcShellBasedSurfaceModel, or an IfcFaceBasedSurfaceModel. In some cases it may also be useful to expose a simple representation as a bounding box representation of the same complex shape.
Body SurfaceOrSolidModel Geometry	General	Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a mixed representation, including surface and solid models.
Body SweptSolid Composite Geometry	General	No description available.
Body SweptSolid CompositeCurve Geometry	General	No description available.
Body SweptSolid ParameterizedProfile Geometry	General	No description available.
Body SweptSolid PolyCurve Geometry	General	No description available.
Body Tessellation Geometry	Reference View	Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple tessellated surface models, in particular triangulated surface models.
Box Geometry	General	This is a further elaboration on an inherited concept. Figure 5.4.3.40.C — Building element box representation EXAMPLE Any IfcElement may be represented by a bounding box, which shows the maximum extent of the body within the object coordinate system established by the IfcObjectPlacement. As shown in Figure 5.4.3.40.C, the bounding box representation is given by an IfcShapeRepresentation that includes a single item: an IfcBoundingBox.
CoG Geometry	General	This is a further elaboration on an inherited concept. The 'CoG', Center of Gravity, shape representation is used as a means to verify the correct import by comparing the CoG of the imported geometry with the explicitly provided CoG created during export.
Element Interference	General	No description available.
Element Nesting	General	A host element can nest connected components. This should be used when there is a specific position or form factor to attach specific elements. EXAMPLE A sink has a pre-drilled hole to attach a faucet.
Element Projecting	General	No description available.
Element Voiding Features	General	No description available.
FootPrint Annotation Geometry	General	No description available.
FootPrint GeomSet PolyCurve Geometry	General	No description available.
FootPrint Geometry	General	No description available.
Mapped Geometry	General	This is a further elaboration on an inherited concept. Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented using the 'MappedRepresentation'. This shall be supported as it allows for reusing the geometry definition of a type at all occurrences of the same type. The results are more compact data sets. The same constraints, as given for 'SurfaceOrSolidModel', 'SurfaceModel', 'Tessellation', 'Brep', and 'AdvancedBrep' geometric representation, shall apply to the IfcRepresentationMap.
Product Grid Placement	General	No description available.
Product Linear Placement	General	Product placement with a Product Linear Placement template. It defines the local coordinate system based on the curve which is referenced by IfcLinearPlacement.RelativePlacement which is an IfcAxis2PlacementLinear.Location using an IfcPointByDistanceExpression.BasisCurve. The local coordinate system is based on the tangent of the curve at Location, its normal in the global Z plane and the cross product of the aforementioned vectors.
Product Local Placement	General	This is a further elaboration on an inherited concept. The object placement for any subtype of IfcElement is defined by the IfcObjectPlacement, either IfcLocalPlacement or IfcGridPlacement, which defines the local object coordinate system that is referenced by all geometric representations of that IfcElement.
Property Sets for Objects	General	This concept can be applied to the following resources: Pset_Condition Pset_InstallationOccurrence Pset_MaintenanceStrategy Pset_MaintenanceTriggerCondition Pset_MaintenanceTriggerDuration Pset_MaintenanceTriggerPerformance Pset_RepairOccurrence Pset_ConstructionAdministration Pset_ConstructionOccurence Pset_ElementKinematics Pset_EnvironmentalCondition Pset_EnvironmentalImpactIndicators Pset_EnvironmentalImpactValues Pset_ManufacturerOccurrence Pset_ManufacturerTypeInformation Pset_ServiceLife Pset_Warranty
Surface Feature Adherence	General	No description available.
Surface Sectioned Geometry	General	No description available.
Surface Tessellation Geometry	General	No description available.
Body AdvancedSweptSolid Geometry	General	No description available.
Body Clipping Geometry	General	No description available.
Body SweptSolid Geometry	General	No description available.
Element Covering	General	No description available.
Element Occurrence Attributes	General	No description available.
Element Voiding	General	No description available.
Lighting Geometry	General	No description available.
Object Typing	General	This concept can be applied to the following resources: IfcElementType
Profile 3D Geometry	General	No description available.
Profile Geometry	General	No description available.
Spatial Containment	General	This concept can be applied to the following resources: IfcSpatialElement
Surface 3D Geometry	General	No description available.
Surface Geometry	General	No description available.
IfcFeatureElement (1)
Spatial Containment	General	This is a further elaboration on an inherited concept. As a subordinate part being fully dependent on the master element the IfcFeatureElement shall have no independent containment relationship to the spatial structure. The SELF\IfcElement.ContainedInStructure relationship shall be NIL.
Click to show 79 hidden inherited concepts
IfcOpeningElement (7)
Body SweptSolid Geometry	General	This is a further elaboration on an inherited concept. The 'Body' representation of IfcOpeningElement can be represented using the representation types 'SweptSolid'. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used: IfcShapeRepresentation.RepresentationIdentifier: 'Body' IfcShapeRepresentation.RepresentationType: 'SweptSolid' The following constraints are recommended: IfcShapeRepresentation.Items may include a single, or multiple, instances of IfcExtrudedAreaSolid. IfcExtrudedAreaSolid.SweptArea shall support IfcRectangleProfileDef, IfcCircleProfileDef and IfcArbitraryClosedProfileDef. If multiple instances of IfcExtrudedAreaSolid are used, the extrusion direction of each extrusion should be equal. If parametric profiles are used, the parameters may be interpreted to be the dimensions of the opening: IfcRectangleProfileDef.YDim interpreted as opening height IfcRectangleProfileDef.XDim interpreted as opening width There are two main extrusion directions: perpendicular and parallel. Perpendicular Swept Solid Representation Type For a perpendicular swept solid, IfcExtrudedAreaSolid.ExtrudedDirection shall extrude the profile perpendicular to the element it is voiding. This may be horizontal for wall openings, or vertical for floor openings. Figure 5.4.3.40.D — Opening with full extrusion Figure 5.4.3.40.E — Opening with recess extrusion NOTE The local placement directions for the IfcOpeningElement in Figure 5.4.3.40.D and Figure 5.4.3.40.E are only given as an example; other directions are valid as well. NOTE Rectangles are now defined centrally, so the placement location has to be set to IfcCartesianPoint(XDim/2,YDim/2) Parallel Swept Solid Representation Type For a parallel swept solid,IfcExtrudedAreaSolid.ExtrudedDirection shall extrude the profile parallel to the element it is voiding. This may be vertical in the case of walls. Parallel extrusions shall be used when an opening or recess has a non rectangular foot print geometry that does not change along the height of the opening or recess. Figure 5.4.3.40.F shows a vertical extrusion with multiple extrusion bodies for the opening. Each extrusion body has a different extrusion length. Figure 5.4.3.40.F — Opening with multiple extrusions NOTE The local placement directions for the IfcOpeningElement in Figure 5.4.3.40.F are only given as an example, other directions are valid as well.
Product Local Placement	General	This is a further elaboration on an inherited concept. The local placement for IfcOpeningElement 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 PlacementRelTo relationship of IfcLocalPlacement should point to the local placement of the element which is voided by the opening, i.e. referred to by VoidsElement.RelatingBuildingElement.
Property Sets for Objects	General	This is a further elaboration on an inherited concept. This concept can be applied to the following resources: Pset_OpeningElementCommon
Quantity Sets	General	This concept can be applied to the following resources: Qto_OpeningElementBaseQuantities
Reference Geometry	General	This is a further elaboration on an inherited concept. Since there are no Boolean operations, either as IfcBooleanResult or implicitly by IfcRelVoidsElement, the geometry of the IfcOpeningElement shall not be used to subtract the opening from the 'Body' shape representation of the voided element.
Reference SweptSolid PolyCurve Geometry	General	This is a further elaboration on an inherited concept. Since there are no Boolean operations, either as IfcBooleanResult or implicitly by IfcRelVoidsElement, the geometry of the IfcOpeningElement shall not be used to subtract the opening from the 'Body' shape representation of the voided element.
Reference Tessellation Geometry	General	This is a further elaboration on an inherited concept. Since there are no Boolean operations, either as IfcBooleanResult or implicitly by IfcRelVoidsElement, the geometry of the IfcOpeningElement shall not be used to subtract the opening from the 'Body' shape representation of the voided element.

5.4.3.40.7 Examples

Figure 5.4.3.40.G

Slab Openings

5.4.3.40.8 Formal representation

 ENTITY IfcOpeningElement
 SUBTYPE OF (IfcFeatureElementSubtraction);
	PredefinedType : OPTIONAL IfcOpeningElementTypeEnum;
 INVERSE
	HasFillings : SET [0:?] OF IfcRelFillsElement FOR RelatingOpeningElement;
 WHERE
	CorrectPredefinedType : NOT(EXISTS(PredefinedType)) OR
 (PredefinedType <> IfcOpeningElementTypeEnum.USERDEFINED) OR
 ((PredefinedType = IfcOpeningElementTypeEnum.USERDEFINED) AND EXISTS (SELF\IfcObject.ObjectType));
END_ENTITY;