Although they address diverse domains, these six reports reveal a set of common criteria for high assurance. Generally speaking, the critical criteria are reliability, availability, safety, timeliness, security, and evolvability. These reports also identify areas for study: ? In "Passive Safety in High-Consequence Systems," Victor L. Winter, John M. Covan, and Larry J. Dalton discuss the design principles behind passive safety, which means that a system is not required to initiate any action to arrive at a safe state. ? In "Long-Life Deep-Space Applications," Leon Alkalai and Ann T. Tai describe the design philosophy behind a highly miniaturized, reliable, low-cost, avionics system for long-life deep-space applications. ? In "Challenges for Continuously Available Systems," Rick Harper and Barry Flahive tell about continuously available systems, which are used whenever the cost of downtime is extremely high. They describe a data-base server that directs certain telephone calls via service control points. ? In "Capturing Safety-Critical Medical Requirements," Wei-Tek Tsai, Ramin Mojdehbakhsh, and Sanjai Rayadurgam discuss safety, reliability, and timing issues associated with medical devices such as pacemakers and defibrillators. ? In "Applications in Rapidly Changing Environments," Kinji Mori dis cusses application systems requirements designed to accommodate the rapid advances in computer and communication technologies. ? In "Component-Based Reconfigurable Systems," Michael R. Lowry describes NASA Ames? Amphion project, a system for building high-assurance reconfigurable software systems from components in a software library.