IfcRelVoidsElement

BACnet MVD

#### IfcRelVoidsElement

Natural language names

| Abzug / Subtraktion von Teil aus Element - Relation
| Rel Voids Element
| Relation de percement

Change log

Item | SPF | XML | Change | Description
--- | --- | --- | --- | ---
IFC2x3 to IFC4
IfcRelVoidsElement |  |  |  |
OwnerHistory |  |  | MODIFIED | Instantiation changed to OPTIONAL.
IFC4 Addendum 2
IfcRelVoidsElement |  |  |  |
RelatingBuildingElement |  | X | MODIFIED | Xsdformat changed from Attribute to Hidden.

##### Semantic definitions at the entity

Entity definition

IfcRelVoidsElement is an objectified relationship between a building element and one opening element that creates a void in the element. It is a one-to-one relationship. This relationship implies a Boolean operation of subtraction between the geometric bodies of the element and the opening.

As shown in Figure 182, the insertion of a void into a wall is represented by the relationship IfcRelVoidsElement. The opening is created within the wall by IfcWall(StandardCase) o-- IfcRelVoidsElement --o IfcOpeningElement.

Figure 182 — Relationship for element voiding

> HISTORY New entity in IFC1.0

Attribute definitions

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---

5

RelatingBuildingElement

IfcElement

Reference to element in which a void is created by associated feature subtraction element.

> IFC2x CHANGE The data type has been changed from IfcBuildingElement to IfcElement with upward compatibility for file based exchange.

X

6

RelatedOpeningElement

IfcFeatureElementSubtraction

Reference to the feature subtraction element which defines a void in the associated element.

> IFC2x CHANGE The data type has been changed from IfcOpeningElement to IfcFeatureElementSubtraction with upward compatibility for file based exchange.

X

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
IfcRoot
1 | GlobalId | IfcGloballyUniqueId |  | Assignment of a globally unique identifier within the entire software world. | X | X

2

OwnerHistory

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 in stored - either as addition, deletion or modification.

> IFC4 CHANGE The attribute has been changed to be OPTIONAL.

X

X

3 | Name | 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. | X | X
4 | Description | IfcText | ? | Optional description, provided for exchanging informative comments. |  | X
IfcRelationship
IfcRelDecomposes
IfcRelVoidsElement

5

RelatingBuildingElement

IfcElement

Reference to element in which a void is created by associated feature subtraction element.

> IFC2x CHANGE The data type has been changed from IfcBuildingElement to IfcElement with upward compatibility for file based exchange.

X

6

RelatedOpeningElement

IfcFeatureElementSubtraction

Reference to the feature subtraction element which defines a void in the associated element.

> IFC2x CHANGE The data type has been changed from IfcOpeningElement to IfcFeatureElementSubtraction with upward compatibility for file based exchange.

X

##### Definitions applying to Design Transfer View

Concept inheritance

# | Concept | Template | Model View
--- | --- | --- | ---
IfcRoot
| Revision Control | Revision Control | Design Transfer View

##### Definitions applying to BACnet View

Concept inheritance

# | Concept | Template | Model View
--- | --- | --- | ---
IfcRoot
| Revision Control | Revision Control | Design Transfer View

##### Examples

- Wall with opening and window
- Slab openings

##### Formal representations

XML Specification
`<xs:element name="IfcRelVoidsElement" type="ifc:IfcRelVoidsElement" substitutionGroup="ifc:IfcRelDecomposes" nillable="true"/>
<xs:complexType name="IfcRelVoidsElement">
<xs:complexContent>
<xs:extension base="ifc:IfcRelDecomposes">
<xs:sequence>
<xs:element name="RelatedOpeningElement" type="ifc:IfcFeatureElementSubtraction" nillable="true"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcRelVoidsElement
SUBTYPE OF (IfcRelDecomposes);
RelatingBuildingElement : IfcElement;
RelatedOpeningElement : IfcFeatureElementSubtraction;
END_ENTITY;

EXPRESS-G diagram

`

References: IfcElement IfcFeatureElementSubtraction

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