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The terms "conversational" and "extensible" are defined and shown to be useful properties of computer animation systems. A conversational extensible system for the animation of shaded images is then described. With this system, implemented on a minicomputer, the animator can sketch images and movements freehand, or can define them algorithmically via the Smalltalk language. The system is itself implemented in Smalltalk, and hence can be easily extended or mcdified to suit the animator's personal style.
Ronald M. Baecker (1976) studied this question.