8.6.3.1 IfcClassification
8.6.3.1.1 Semantic definition
An IfcClassification is used for the arrangement of objects into a class or category according to a common purpose or their possession of common characteristics. A classification in the sense of IfcClassification is taxonomy, or taxonomic scheme, arranged in a hierarchical structure. A category of objects relates to other categories in a generalization-specialization relationship. Therefore the classification items in an classification are organized in a tree structure.
The IfcClassification identifies the classification system or source to which a classification reference refers to. Each classification reference may reference an instance of IfcClassification. A classification system declared may be either formally published, or it may be a locally defined method of classifiying information.
There are two methods to define and reference a classification system:
- Including the classification system structure within the dataset: Here a hierarchical tree of IfcClassificationReference's is included that defines the classification system including the relationship between the classification items. The ReferencedSource attribute of IfcClassificationReference links the classification item to the parent item, and the parent item finally to the IfcClassification.
- Referencing the classification system by a classification key or id: Here the IfcClassificationReference is used to assign a classification id or key as Identification attribute and it may link by ReferencedSource attribute directly to the IfcClassification.
8.6.3.1.2 Entity inheritance
8.6.3.1.3 Attributes
| # | Attribute | Type | Description |
|---|---|---|---|
| IfcClassification (9) | |||
| 1 | Source | OPTIONAL IfcLabel |
Source (or publisher) for this classification. |
| 2 | Edition | OPTIONAL IfcLabel |
The edition or version of the classification system from which the classification notation is derived. |
| 3 | EditionDate | OPTIONAL IfcDate |
The date on which the edition of the classification used became valid. |
| 4 | Name | IfcLabel |
The name or label by which the classification used is normally known. |
| 5 | Description | OPTIONAL IfcText |
Additional description provided for the classification. |
| 6 | Specification | OPTIONAL IfcURIReference |
Resource identifier or locator, provided as URI, URN or URL, of the classification. |
| 7 | ReferenceTokens | OPTIONAL LIST [1:?] OF IfcIdentifier |
The delimiter tokens that are used to mark the boundaries of individual facets (substrings) in a classification reference. This typically applies then the IfcClassification is used in conjunction with IfcClassificationReference's. If only one ReferenceToken is provided, it applies to all boundaries of individual facets, if more than one ReferenceToken are provided, the first token applies to the first boundary, the second token to the second boundary, and the n^th^ token to the n^th^ and any additional boundary. |
| ClassificationForObjects | SET [0:?] OF IfcRelAssociatesClassification FOR RelatingClassification |
The classification with which objects are associated. |
|
| HasReferences | SET [0:?] OF IfcClassificationReference FOR ReferencedSource |
The classification references to which the classification applies. It can either be the final classification notation, or an intermediate classification item. |
|
8.6.3.1.4 Formal representation
ENTITY IfcClassification
SUBTYPE OF (IfcExternalInformation);
Source : OPTIONAL IfcLabel;
Edition : OPTIONAL IfcLabel;
EditionDate : OPTIONAL IfcDate;
Name : IfcLabel;
Description : OPTIONAL IfcText;
Specification : OPTIONAL IfcURIReference;
ReferenceTokens : OPTIONAL LIST [1:?] OF IfcIdentifier;
INVERSE
ClassificationForObjects : SET [0:?] OF IfcRelAssociatesClassification FOR RelatingClassification;
HasReferences : SET [0:?] OF IfcClassificationReference FOR ReferencedSource;
END_ENTITY;