On defining requirements for interaction

Requirements that involve the usability of systems can be properties of interactions rather than systems alone. This proposition is demonstrated by means of four examples. The authors suggest that a notation like CSP (communicating sequential processes) may be used to provide a framework for considering different modeling approaches. Interaction requirements that relate to multiwindowed systems, walk up and use systems, and dynamic systems such as power stations are considered. It is shown how models provide different representations to which advice from the different disciplines of human computer interaction may be applied