US&R

Abstract

US&R (which stands for Undo, Skip, & Redo ) is a new interactive approach to user recovery that offers significant advantages over current Undo/Redo packages. In the US&R package, a SKIP or REDO command may be ambiguous, in which case US&R enumerates the logical interpretations of the command and prompts the user both textually and graphically for the desired choice. US&R also allows new commands to be executed during the redo process. With US&R, novices can perform recoveries that might be difficult or impossible to do with other systems; experienced users can take even greater advantage of its functionality. US&R's data structure organizes the recovery information in a natural tree-like fashion that is easy to implement in a variety of interactive settings, including text editors, graphics layout systems, algorithm simulators, and program development systems.