The UAN: a user-oriented representation for direct manipulation interface designs

Many existing interface representation techniques, especially those associated with UIMS, are constructional and focused on interface implementation, and therefore do not adequately support a user-centered focus. But it is in the behavioral domain of the user that interface designers and evaluators do their work. We are seeking to complement constructional methods by providing a tool-supported technique capable of specifying the behavioral aspects of an interactive system-the tasks and the actions a user performs to accomplish those tasks. In particular, this paper is a practical introduction to use of the User Action Notation (UAN), a task- and user-oriented notation for behavioral representation of asynchronous, direct manipulation interface designs. Interfaces are specified in UAN as a quasihierarchy of asynchronous tasks. At the lower levels, user actions are associated with feedback and system state changes. The notation makes use of visually onomatopoeic symbols and is simple enough to read with little instruction. UAN is being used by growing numbers of interface developers and researchers. In addition to its design role, current research is investigating how UAN can support production and maintenance of code and documentation.