An interaction engine for rich hypertexts

In semantically rich hypertexts it is attractive to enable presentation of a network of nodes and link at different levels of abstraction. It is also important that the user can interact with the hypertext using a command repertoire that reflects the chosen abstraction level. Based on a characterization of rich hypertext we introduce the concept of an interaction engine that governs the separation between internal hypertext representation and external screen presentation. This separation is the key principle of the HyperPro system. The HyperPro interaction engine is based on simple rules for presentation, interpretation of events, and menu set up. Much of the power of the interaction engine framework comes from the organization of these rules relative to the type of hierarchy of nodes and links, and relative to a hierarchy of so-called interaction schemes. The primary application domain discussed in the paper is program development and program documentation.