“…With respect to a timeline approach 1,3,24,28,30 , a description based on graphs 14,21,34 , flow-charts 22 and virtual timelines 7 is more flexible, since it does not depend on the actual length of the media items. On the other hand, the timeline description is more intuitive, since it is not always easy to capture the real presentation evolution from an event based description like a graph.…”