Abstract: An event occurrence graph for display of events from a monitoring device or set of devices has a time-series of recorded events as a timeline, each event having a separate marker. Different event groups in the time-series occur at different levels, and the markers for the events in each event group may be distinctive from markers for the events in other event groups. Also lines may be drawn connecting start and stop events within an event group. The timeline may be zoomed, and the time scale adjusted automatically accordingly.