对象化关系（ifcreassociateslibrary）处理将库项（select IfcLibrarySelect的项）分配给IfcObjectDefinition或IfcPropertyDefinition的子类型。
此关系用于将库引用或指向库信息的更详细链接指定给对象、特性集或类型。一个库引用可以应用于多个项。
继承的属性RelatedObjects定义应用库关联的项。属性RelatingLibrary是对应用于项的库引用的引用。
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 |
| IfcRelAssociatesLibrary | |||||
| 6 | RelatingLibrary | IfcLibrarySelect | [1:1] | 对库的引用，从中获取属性集的定义。 | X |