1. Events can be sent to models started by the caller (the child models) by using the first form of the procedure and to the model having started the caller (the parent model) with the second form of the procedure. An event can be received only by a running model using the mmjobs module: sending an event to a model that is not running or not using mmjobs is a no-operation.

2. Events are characterized by a class and a value. Event class values can be used to indicate the cause of the event (for instance, 2 could mean `a new solution has been found') and the associated value may specify a property of the given instance (for example an objective value). Except for the special value 1 ( EVENT_END) class values have no predefined meaning.

3. An event of class EVENT_END (=1) and model status as the event value is automatically sent by each model to its parent model when it terminates its execution.