Abstract: An interactive system has a component which manages interactions with the user and a component which manages data transformations. Communication between the interactive component and the data transformation component is by means of a state manager component. The state manager component includes an expected state description, which describes operation of the interactive system as a set of states and transitions therebetween, and an active state description, which describes as much of the present and past state of the interactive system as is required to determine the next state and to "back out" of the present state is response to user inputs specifying "cancel" or "undo" operations.