Read First: Event Type Gives the goals of the operation, or more specifically, the noteworthy effects of the operation. Operations may have other effects that are not modelled in the resulting event types. This just means that the unmodelled effects won't be triggering other operations (see Trigger Rule). The user may still output information about these other effects through output variables (see outputs/IsOutputBy). Operations may have no resulting event at all, for example operations that never finish, like Sell Products. See discussion at Trigger Rule about how events are used in Event Diagrams. Multiple events? See p 170 of the Foundation book. Miscellaneous The minimum cardinality is zero on the Event Type side because some operations do not result in noteworthy events. For example, processes that are not intended to end, likes Sales.