对象化关系ifcreassociatesclassion处理将分类项（select ifccclassificationselect的项）分配给对象引用（IfcObject的子类型）或对象类型（IfcTypeObject的子类型）。
该关系用于将分类项或分类系统本身分配给对象。根据中继分类的类型，它可以是：
对外部分类系统中分类项目的引用，或
提到分类系统本身
注意，对分类项的引用包括指向声明该项的分类系统的链接。它将分类项的含义指定给对象（ocurrence或type）。对分类系统的引用提供了对象（事件或类型）受分类系统控制的信息，但尚未完成特定项的分配。
继承的属性RelatedObjects定义应用分类的对象或对象类型。属性RelatingClassification是对应用于对象的分类的引用。因此，单个中继分类可应用于一个或多个对象。
在IFC2x中增加的新实体。
| # | Attribute | Type | Cardinality | Description | C |
|---|---|---|---|---|---|
| IfcRoot | |||||
| 1 | GlobalId | IfcGloballyUniqueId | [1:1] | Assignment of a globally unique identifier within the entire software world. | X |
| 2 | OwnerHistory | IfcOwnerHistory | [0:1] | 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 - either as addition, deletion or modification. |
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 |
| IfcRelationship | |||||
| IfcRelAssociates | |||||
| 5 | RelatedObjects | IfcDefinitionSelect | S[1:?] | 与外部引用或信息关联的对象或属性定义集。它包括对象和类型对象、属性集模板、属性模板以及属性集和上下文。 | X |
| IfcRelAssociatesClassification | |||||
| 6 | RelatingClassification | IfcClassificationSelect | [1:1] | Classification applied to the objects. | X |