A brief overview of the requirements engineering, its history, and state of practice are given. A semi-formal method to structure the behavioral requirements for real-time embedded systems is presented. This method is based on a set of forms that contain both informal text-based descriptions and formally defined language constructs. After documentation of requirements into these forms, an algorithm to automatically generate event scenarios is presented. This algorithm extracts the needed information from the requirements forms and produces a set of scenarios that can be used to test transaction oriented systems. A design example is presented that is used to illustrate the process of converting text based requirements onto the structured requirements form and to illustrate the operation of the scenario generation algorithm