IFC 4.3.1.0 (IFC4X3_ADD1)

# 8.6.3.2 IfcClassificationReference

## 8.6.3.2.1 Semantic definition

An IfcClassificationReference is a reference into a classification system or source (see IfcClassification) for a specific classification key (or notation).

The inherited attributes have the following meaning:

• Identification: holds the key provided for a specific references to classification items (or tables).
• Name: allows for a human interpretable designation of a classification notation.
• Location: optionally holds a direct URI link into the classification system (or source) to hyperlink the classification key.

The IfcClassificationReference can either be assigned directly to the IfcClassification, such as if no classification hierarchy has to be included, or it references the parent classification notation, if the fully classification hierarchy is included in the data set. The first is referred to as "lightweight classification", and the second as "full classification". The attribute ReferencedSource then holds the following information (choice by IfcClassificationReferenceSelect):

1. being of type IfcClassification: direct reference to the classification system (with meta information provided);
2. being of type IfcClassificationReference: reference to the parent classification notation within the classification hierarchy.

## 8.6.3.2.4 Formal representation

ENTITY IfcClassificationReference
SUBTYPE OF (IfcExternalReference);
ReferencedSource : OPTIONAL IfcClassificationReferenceSelect;
Description : OPTIONAL IfcText;
Sort : OPTIONAL IfcIdentifier;
INVERSE
ClassificationRefForObjects : SET [0:?] OF IfcRelAssociatesClassification FOR RelatingClassification;
HasReferences : SET [0:?] OF IfcClassificationReference FOR ReferencedSource;
END_ENTITY;