The authors of this book explore the requirements of modeling of real-time systems. Traditional flowcharts assume processes occur sequentially, which although frequently elegant in design, are not rich enough to describe real-time systems. The descriptions of some of the models in the book will appear familiar to testers. The essential model, for example, describes the required behavior of a system--much as sophisticated testers build sample cases to serve as models for a proposed system to judge adequacy of requirements. In 156 pages, the book offers well-written, easy-to-digest text on the modeling of real-time systems.