8.6.3.10 IfcLibraryReference
8.6.3.10.1 Semantic 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.
Depending on the type of technology used by the library, different IfcLibraryReference.Identification identifiers will be appropriate:
| Publisher | Technology | Identifier |
|---|---|---|
| ASHRAE | BACnet | 32-bit decimal BACnetObjectIdentifier indicating type ID and instance ID (e.g.'12.15' for Digital Input #15). |
| Brick Development Team | Brick | Full URI with no namespace (e.g. 'http://example.org/digitaltwin#AHU01') |
| IETF | IPv4 | 32-bit decimal address for an IPv4 network (e.g.'192.168.1.1'). |
| IETF | IPv6 | 128-bit hexadecimal address for an IPv6 network. |
| IETF | MAC | 48-bit hexadecimal form of MAC address. |
| ISOIEC | LonTalk | 48-bit hexadecimal neuron ID. |
| OPCFoundation | OPC | Hierarchical ItemID in alphanumeric form (i.e. 'B204.Tank2.Temperature) |
| SmartLabs | Insteon | 24-bit hexadecimal instance address. |
8.6.3.10.2 Entity inheritance
8.6.3.10.3 Attributes
| # | Attribute | Type | Description |
|---|---|---|---|
| IfcExternalReference (4) | |||
| 1 | Location | OPTIONAL 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. |
| 2 | Identification | OPTIONAL 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). |
| 3 | Name | OPTIONAL 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). |
| ExternalReferenceForResources | SET [0:?] OF IfcExternalReferenceRelationship FOR RelatingReference |
Reference to all associations between this external reference and objects within the IfcResourceObjectSelect that are tagged by the external reference. |
|
| Click to show 4 hidden inherited attributes Click to hide 4 inherited attributes | |||
| IfcLibraryReference (4) | |||
| 4 | Description | OPTIONAL IfcText |
Additional description provided for the library reference. |
| 5 | Language | OPTIONAL IfcLanguageId |
The language in which a library reference is expressed. |
| 6 | ReferencedLibrary | OPTIONAL IfcLibraryInformation |
The library information that is being referenced. |
| LibraryRefForObjects | SET [0:?] OF IfcRelAssociatesLibrary FOR RelatingLibrary |
The library reference with which objects are associated. |
|
8.6.3.10.4 Formal representation
ENTITY IfcLibraryReference
SUBTYPE OF (IfcExternalReference);
Description : OPTIONAL IfcText;
Language : OPTIONAL IfcLanguageId;
ReferencedLibrary : OPTIONAL IfcLibraryInformation;
INVERSE
LibraryRefForObjects : SET [0:?] OF IfcRelAssociatesLibrary FOR RelatingLibrary;
END_ENTITY;