#### IfcFeatureElement

Natural language names

##### Semantic definitions at the entity

Entity definition

Generalization of all existence dependent elements which modify the shape and appearance of the associated master element. The IfcFeatureElement offers the ability to handle shape modifiers as semantic objects within the IFC object model.

> NOTE The term "feature" has a predefined meaning in a context of "feature-based modeling" and within steel construction work. It is introduced here in a broader sense to cover all existence dependent, but semantically described, modifiers of an element's shape and appearance. It is envisioned that future releases enhance the feature-based capabilities of the IFC model.

In contrary to the aggregation, as used in IfcElementAssembly, that defines the aggregate as a container element, that has equally treated parts, the feature concept introduced by IfcFeatureElement defines the master element with subordinate parts as additions, or with voids or cut-outs as subtractions.

> 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.

Containment Use Definition

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.

Geometry Use Definition

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

Local Placement

The local placement for IfcFeatureElement 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 shall point (if given) to the local placement of the master IfcElement (its relevant subtypes), which is associated to the IfcFeatureElement by the appropriate relationship object.
- If the relative placement is not used, the absolute placement is defined within the world coordinate system.

Shape Representation

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

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | A
--- | --- | --- | --- | --- | ---
IfcRoot
1 | GlobalId | IfcGloballyUniqueId | [1:1] | Assignment of a globally unique identifier within the entire software world. | X
2 | OwnerHistory | IfcOwnerHistory | [1:1] | 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. | 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
IfcObjectDefinition
| IsDecomposedBy | IfcRelDecomposes @RelatingObject | S[0:?] | Reference to the decomposition relationship, that allows this object to be the composition of other objects. An object can be decomposed by several other objects. | X
| Decomposes | IfcRelDecomposes @RelatedObjects | S[0:1] | References to the decomposition relationship, that allows this object to be a part of the decomposition. An object can only be part of a single decomposition (to allow hierarchical strutures only). | X
| HasAssociations | IfcRelAssociates @RelatedObjects | S[0:?] | 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. | X
IfcObject
5 | ObjectType | IfcLabel | [0:1] | 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. | X
| IsDefinedBy | IfcRelDefines @RelatedObjects | S[0:?] | Set of relationships to type or property (statically or dynamically defined) information that further define the object. In case of type information, the associated IfcTypeObject contains the specific information (or type, or style), that is common to all instances of IfcObject referring to the same type. | X
IfcProduct
6 | ObjectPlacement | IfcObjectPlacement | [0:1] | 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 constraint (e.g. relative to grid axes). It is determined by the various subtypes of IfcObjectPlacement, which includes the axis placement information to determine the transformation for the object coordinate system. | X
7 | Representation | IfcProductRepresentation | [0:1] | Reference to the representations of the product, being either a representation (IfcProductRepresentation) or as a special case a shape representations (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. | X
IfcElement
8 | Tag | - |  | This attribute is out of scope for this model view definition and shall not be set. |
| ConnectedTo | IfcRelConnectsElements @RelatingElement | S[0:?] | Reference to the element connection relationship. The relationship then refers to the other element to which this element is connected to. |
| HasOpenings | IfcRelVoidsElement @RelatingBuildingElement | S[0:?] | Reference to the Voids Relationship that creates an opening in an element. An element can incorporate zero-to-many openings. | X
| IsConnectionRealization | IfcRelConnectsWithRealizingElements @RealizingElements | S[0:?] | Reference to the connection relationship with realizing element. The relationship then refers to the realizing element which provides the physical manifestation of the connection relationship. | X
| ConnectedFrom | IfcRelConnectsElements @RelatedElement | S[0:?] | Reference to the element connection relationship. The relationship then refers to the other element that is connected to this element. | X
| ContainedInStructure | IfcRelContainedInSpatialStructure @RelatedElements | S[0:1] | Containment relationship to the spatial structure element, to which the element is primarily associated. | X
IfcFeatureElement

##### Formal representations

XSD Specification
`<xs:element name="IfcFeatureElement" type="ifc:IfcFeatureElement" abstract="true" substitutionGroup="ifc:IfcElement" nillable="true"/>
<xs:complexType name="IfcFeatureElement" abstract="true">
<xs:complexContent>
<xs:extension base="ifc:IfcElement"/>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcFeatureElement
ABSTRACT SUPERTYPE OF(IfcFeatureElementSubtraction)
SUBTYPE OF (IfcElement);
END_ENTITY;

EXPRESS-G diagram

`

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