Event model of human-system interaction

Interaction objects (interactors) are abstract structures that provide a link between rigorous approaches to software development and user-oriented aspects of interaction. The focus of the paper is on the second role of interactors; in particular, how a formal model of interaction can be used to classify and clarify various properties of interactive behaviour that are important from a user oriented viewpoint. The formal model used in this discussion abstracts away from distinctions between states, events, and renderings; when needed, these concepts are introduced as various projections on the basic model