Statechart is a visual language for software requirement specification that has been widely used in recent years. In essence, it extends the conventional language of state-transition diagrams with three elements that accommodates the notions of hierarchy, concurrency, and communication. Additionally, it allows multilevel concurrency, creation of chain-reaction effects, and the use of high-and low-level events. It is compact, expressive, compositional, and modular. This paper presents a tutorial

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... of Statechart and discusses its merits and shortcomings.