IfcEvent是触发操作或响应的事件。
IFC4中增加的新实体
IfcEvent用于捕获有关发生或可能发生的特定事情的信息。特别是在工作计划（或流程图）中使用，它们标识了一个点，例如，包含信息的消息可以在该点发出，或者在该点调用规则或约束。
Attribute definitions
| # | Attribute | Type | Cardinality | Description | C |
|---|---|---|---|---|---|
| 8 | PredefinedType | IfcEventTypeEnum | [0:1] | Identifies the predefined types of an event from which the type required may be set. | X |
| 9 | EventTriggerType | IfcEventTriggerTypeEnum | [0:1] | Identifies the predefined types of event trigger from which the type required may be set. | X |
| 10 | UserDefinedEventTriggerType | IfcLabel | [0:1] | A user defined event trigger type, the value of which is asserted when the value of an event trigger type is declared as USERDEFINED. | X |
| 11 | EventOccurenceTime | IfcEventTime | [0:1] | The date and/or time at which an event occurs. | X |
Formal Propositions
| Rule | Description |
|---|---|
| CorrectPredefinedType | Either the PredefinedType attribute is unset, or the inherited attribute ObjectType must be asserted when the value of PredefinedType is set to USERDEFINED. |
| CorrectTypeAssigned | Either the EventTriggerType attribute is unset, or the attribute UserDefinedEventTriggerType must be asserted when the value of EventTriggerType is set to USERDEFINED. |
