对象化关系IfcRelAssignsToGroup处理对象定义（单个对象引用作为IfcObject的子类型，对象类型作为IfcTypeObject的子类型）到组（IfcGroup的子类型）的分配。
该关系处理将组成员分配给组对象的操作。它允许对组中的任意对象进行分组，包括其他组。分组关系可以递归方式应用。结果组的类型为IfcGroup。
●注：组的示例包括分区作为空间组、配电系统作为建筑服务构件组或结构分析模型作为结构项组。
继承的属性RelatedObjects提供对对象的引用，这些对象是组中的元素。RelatingGroup是包含所有元素的组。同一对象或对象类型可以包含在零个、一个或多个组中。分组关系不是分层的。
非正式提议：
■分组分配关系应当是无环的，即一个组不应当参与自己的分组关系。
在IFC1.0中增加的新实体。IFC2x中的IfcRelGroups属性重命名。
| # | 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 | |||||
| IfcRelAssigns | |||||
| 5 | RelatedObjects | IfcObjectDefinition | S[1:?] | Related objects, which are assigned to a single object. The type of the single (or relating) object is defined in the subtypes of IfcRelAssigns. | X |
| 6 | RelatedObjectsType | IfcObjectTypeEnum | [0:1] | Particular type of the assignment relationship. It can constrain the applicable object types, used within the role of RelatedObjects. | X |
| IfcRelAssignsToGroup | |||||
| 7 | RelatingGroup | IfcGroup | [1:1] | Reference to group that contains all assigned group members. | X |