#### IfcRailing

Natural language names

##### Semantic definitions at the entity

Entity definition

Definition of IAI: The railing is a frame assembly adjacent to human circulation spaces and at some space boundaries where it is used in lieu of walls or to complement walls. Designed to aid humans, either as an optional physical support, or to prevent injury by falling. A list of references to accessory/mounting hardware for this railing might be given by including these assessories (IfcDiscreteAssessory) through the objectified relationship IfcRelAggregates.

> HISTORY New Entity in IFC Release 2.0

Property Set Use Definition:

The property sets relating to the IfcRailing are defined by the IfcPropertySet and attached by the IfcRelDefinesByProperties relationship. It is accessible by the inverse IsDefinedBy relationship. The following property set definitions specific to the IfcRailing are part of this IFC release:

- Pset_RailingCommon: common property set for all railing occurrences

Geometry Use Definitions

The geometric representation of IfcRailing is given by the IfcProductDefinitionShape, allowing multiple geometric representations. Included are:

Local placement

The local placement for IfcRailing 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 same IfcSpatialStructureElement that is used in the ContainedInStructure inverse attribute or to a referenced spatial structure element at a higher level
- If the IfcRailing, however, is used by an IfcStair or IfcRamp, and this container class defines its own local placement, then the PlacementRelTo relationship of IfcLocalPlacement shall point (if given) to the local placement of the aggregate.
- If the relative placement is not used, the absolute placement is defined within the world coordinate system.

Geometric Representation

Currently the use of 'BoundingBox', 'SurfaceModel', 'Brep' and 'MappedRepresentation' representations of IfcRailing are supported. The conventions to use these representations are given at the level of the supertype, IfcBuildingElement.

Attribute definitions

# | Attribute | Type | Cardinality | Description | A
--- | --- | --- | --- | --- | ---
9 | PredefinedType | - |  | This attribute is out of scope for this model view definition and shall not be set. |

Formal Propositions

Rule | Description
--- | ---
WR61 | Either the PredefinedType attribute is unset (e.g. because an IfcRailingType is associated), or the inherited attribute ObjectType shall be given, if the PredefinedType is set to USERDEFINED.

##### 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
IfcBuildingElement
IfcRailing
9 | PredefinedType | - |  | This attribute is out of scope for this model view definition and shall not be set. |

##### Definitions applying to AISC Model View

Instance diagram

Concept usage

Properties on Occurrences

The Properties on Occurrences concept applies to this entity as shown in Table 23.

Property
AISC_EM11_Pset_PieceIdentification
AISC_EM11_Pset_Feature
AISC_EM11_Pset_ToleranceForLayout
AISC_EM11_Pset_Material
AISC_EM11_Pset_SurfaceTreatment
AISC_EM11_Pset_StatusInformation
AISC_EM11_Pset_VersionInformation
Table 23 — IfcRailing Properties on Occurrences

Exchange |
--- | ---
Import | O
Export | O

Placement

The Placement concept applies to this entity.

Exchange |
--- | ---
Import | R
Export | R

Body Geometry

The Body Geometry concept applies to this entity.

Exchange |
--- | ---
Import | R
Export | R

Concept alternates

Body AdvancedSweptSolid Geometry

The Body AdvancedSweptSolid Geometry concept applies to this entity.

Exchange |
--- | ---
Import | O
Export | O

Body Brep Geometry PolyLoop

The Body Brep Geometry PolyLoop concept applies to this entity.

Exchange |
--- | ---
Import | O
Export | O

Mapped Geometry

The Mapped Geometry concept applies to this entity.

Exchange |
--- | ---
Import | O
Export | O

Concept inheritance

# | Concept | Model View
--- | --- | ---
IfcRailing
| Properties on Occurrences | AISC Model View
| Placement | AISC Model View
| Body Geometry | AISC Model View
| Mapped Geometry | AISC Model View

##### Formal representations

XSD Specification
`<xs:element name="IfcRailing" type="ifc:IfcRailing" substitutionGroup="ifc:IfcBuildingElement" nillable="true"/>
<xs:complexType name="IfcRailing">
<xs:complexContent>
<xs:extension base="ifc:IfcBuildingElement"/>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcRailing
SUBTYPE OF (IfcBuildingElement);
PredefinedType : OPTIONAL IfcStrippedOptional;
WHERE
WR61 : NOT(EXISTS(PredefinedType)) OR (PredefinedType <> IfcRailingTypeEnum.USERDEFINED) OR ((PredefinedType = IfcRailingTypeEnum.USERDEFINED) AND EXISTS (SELF\IfcObject.ObjectType));
END_ENTITY;

EXPRESS-G diagram

`

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