IfcLibraryReference

BACnet MVD

#### IfcLibraryReference

Natural language names

| Bibliothekseintrag
| Library Reference
| Référence de bibliothèque

Change log

Item | SPF | XML | Change | Description
--- | --- | --- | --- | ---
IFC2x3 to IFC4
IfcLibraryReference |  |  |  |
Location |  |  | MODIFIED | Type changed from IfcLabel to IfcURIReference.
Identification |  | X | MODIFIED | Name changed from ItemReference to Identification.
Description |  |  | ADDED |
Language |  |  | ADDED |
ReferencedLibrary |  |  | ADDED |

##### Semantic definitions at the entity

Entity definition

An IfcLibraryReference is a reference into a library of information by Location (provided as a URI). It also provides an optional inherited Identification key to allow more specific references to library sections or tables. The inherited Name attribute allows for a human interpretable identification of the library item. Also, general information on the library from which the reference is taken, is given by the ReferencedLibrary relation which identifies the relevant occurrence of IfcLibraryInformation.

The ifcLibraryReference additionally provides the capability to handle multilingual library entries. The Language attribute then holds the language tag for the language used by the strings kept in the Name and the Description attribute.

> HISTORY New entity in IFC2.0.

> IFC4 CHANGE Description and Language attribute added; ReferencedLibrary attribute added (reversing previous ReferenceIntoLibrary inverse relationship).

Attribute definitions

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

4

Description

IfcText

?

Additional description provided for the library reference.

> IFC4 CHANGE New attribute added at the end of the attribute list.

X

X

5

Language

IfcLanguageId

?

The language in which a library reference is expressed.

> IFC4 CHANGE New attribute added at the end of the attribute list.

X

X

6 | ReferencedLibrary | IfcLibraryInformation | ? | The library information that is being referenced. | X | X

LibraryRefForObjects

IfcRelAssociatesLibrary
@RelatingLibrary

S[0:?]

The library reference with which objects are associated.

> IFC4 CHANGE New inverse attribute.

X

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

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

1

Location

IfcURIReference

?

Location, where the external source (classification, document or library) can be accessed by electronic means. The electronic location is provided as an URI, and would normally be given as an URL location string.

> IFC4 CHANGE The data type has been changed from IfcLabel to IfcURIReference
> .

X

X

2

Identification

IfcIdentifier

?

The Identification provides a unique identifier of the referenced item within the external source (classification, document or library). It may be provided as

- a key, e.g. a classification notation, like NF2.3
- a handle
- a uuid or guid

It may be human readable (such as a key) or not (such as a handle or uuid) depending on the context of its usage (which has to be determined by local agreement).

> IFC4 CHANGE Attribute renamed from ItemReference for consistency.

X

X

3 | Name | IfcLabel | ? | Optional name to further specify the reference. It can provide a human readable identifier (which does not necessarily need to have a counterpart in the internal structure of the document). | X | X

ExternalReferenceForResources

IfcExternalReferenceRelationship
@RelatingReference

S[0:?]

Reference to all associations between this external reference and objects within the IfcResourceObjectSelect that are tagged by the external reference.

> IFC4 CHANGE New inverse attribute added with upward compatibility.

X

IfcLibraryReference

4

Description

IfcText

?

Additional description provided for the library reference.

> IFC4 CHANGE New attribute added at the end of the attribute list.

X

X

5

Language

IfcLanguageId

?

The language in which a library reference is expressed.

> IFC4 CHANGE New attribute added at the end of the attribute list.

X

X

6 | ReferencedLibrary | IfcLibraryInformation | ? | The library information that is being referenced. | X | X

LibraryRefForObjects

IfcRelAssociatesLibrary
@RelatingLibrary

S[0:?]

The library reference with which objects are associated.

> IFC4 CHANGE New inverse attribute.

X

##### Examples

- Air terminal element

##### Formal representations

XML Specification
`<xs:element name="IfcLibraryReference" type="ifc:IfcLibraryReference" substitutionGroup="ifc:IfcExternalReference" nillable="true"/>
<xs:complexType name="IfcLibraryReference">
<xs:complexContent>
<xs:extension base="ifc:IfcExternalReference">
<xs:sequence>
<xs:element name="ReferencedLibrary" type="ifc:IfcLibraryInformation" nillable="true" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="Description" type="ifc:IfcText" use="optional"/>
<xs:attribute name="Language" type="ifc:IfcLanguageId" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcLibraryReference
SUBTYPE OF (IfcExternalReference);
Description : OPTIONAL IfcText;
Language : OPTIONAL IfcLanguageId;
ReferencedLibrary : OPTIONAL IfcLibraryInformation;
INVERSE
LibraryRefForObjects : SET [0:?] OF IfcRelAssociatesLibrary FOR RelatingLibrary;
END_ENTITY;

EXPRESS-G diagram

`

References: IfcLibraryInformation IfcLibrarySelect

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