Alexander[1,2], in developing his architectural patterns visited ``places that worked'' to gather the characteristics of these places for later analysis. While it would be possible to examine interactive systems in this same way, it was our opinion that the literature already contains patterns and nascent patterns in the form of the many principles and guidelines that have been articulated. These principles and guidelines endeavor to abstract the characteristics of ``interfaces that work.'' Design principles for interactive systems abound in the literature. It was our initial belief that many of the operational principles in the literature would be more concrete and particular than the patterns. Similarly, we felt that the more conceptual principles might be very close to patterns, subsuming other principles. We sought patterns in line with what Thimbleby[18, p 202,] has referred to as "generative user engineering principles." That is, a pattern should be easy to instantiate in a given situations and it should provide specific guidance about what should be done. Our contention was that a pattern such as ``provide for ordered information" would be more easily understood and used than an abstract high level principle such as Norman's ``reduce the gulf of evaluation''.