Abstract
This paper introduces hypercharts, a novel and effective model that extends the well-known statechart formalism to make it suitable for the specification of the temporal and information synchronization requirements of hypermedia applications. Three new definitions are added: timed history, timed transitions and a set of synchronization mechanisms. The proposed extensions are based on the major characteristics of some Petri net based multimedia models, and have their semantics described in the paper in terms of conventional statechart models.