Here we will define an Event as a “happening at a point in time”.  We will define a Trigger as an event that requires a response, even if the response may end up being “no action required”. Since the definition of a trigger may be contextual (the same event may require responses from some groups only) then it may be best to model this as a role (Event plays role of Trigger).<br/>A ProjectMilestone is modeled as an Activity rather than as an Event, so that it is a type of ProjectElement and can form part of a Project. <br/>There will be Triggers that may cause the generation of an Activity. For example, a network fault, Customer complaint or network infrastructure run-out. Also, completion of a ProjectMilestone may generate events e.g. payment to a Contractor.<br/><i>Note: This part of the model may change when the SID Event model is defined.</i><br/>