ABSTRACT
Design in behavioral terms has a cyclical history (initial design analysis, detailed design, design testing, and production). Design is also viewed as an information processing problem. Successful design depends on answering a number of questions which are listed in Table 1. These question, to which there are no automatically correct answers, will have to be answered again and again as the design becomes more detailed, because changes in design detail required changed answers. The answers to subsequent questions may also require a change in the answers to previous questions; much design involves this kind of feedback. For this reasons one cannot think of SEP design as a linear process.
