As software systems continue to increase in sophistication and complexity, so do the interface requirements that support the corresponding user interaction. To select the proper ' ' nd of ingredients that constitutes an adequate user interface, it is essential that the system designer have a firm understanding of the interaction process, i.e, how the selected dialogue format interacts with the user and with the underlying task software. To promote such an understanding, this paper presents a model that characterizes one particular dialogue for menu-based interaction. This model is actually a sequence of models, hierarchically structured, where each successive model builds on its predecessor by introducing additional characterization elements. The first model describes the minimal set of elements inherent to any menu-based interface; successive models extend this minimal set by introducing task actions, incremental history sequences, and frame-associated memory. These principal model elements enable the characterization of fundamental, menu-based operations like computational and decision processes, user response reversal, and user directed movement. Moreover, because the principal model elements correspond directly to real world objects, an intuitive as well as formal understanding of menu-based interaction can be achieved. Effectively, the model elements and the hierarchical structure imposed by these elements provide and ideal environment for characterizing and classifying menu-based systems at various levels of sophistication
