1. An event can be received only by a running model that is 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 ( XPRD_EVENT_END) class values have no predefined meaning.

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