Correct mapping for an Event with ActiveState|OPC UA Standard|Forum|OPC Foundation

With the BaseEventType and its extensions, it´s possible to define a condition considered important, which can trigger an event notification. This notification just tells that that condition has happened, or in a more basic example, a boolean variable went from FALSE to TRUE.

Now, if I need to represent into OPC UA an event with start and finish conditions (like a boolean variable going from FALSE to TRUE, and then back to FALSE) with start and end times, it´s not clear what would be the best approach.

The AlarmConditionType implements the ActiveState property (which is what i need), but it is an extension from the AcknowledgeableConditionType, which is an overhead, because the acknowledgement of such type of event is not necessary.

So I think about 2 possibilities:

a) I could extend the ConditionType and create a custom type that implements the ActiveState concept;

b) I could use the AlarmConditionType in a way that events raised are already acknowledged.

Which one is the best? Or there are another way that is not clear for me at the moment. Thanks!