Troubleshooting - the process of locating and diagnosing a fault in a system - is often difficult for the maintenance specialist in a computer controlled manufacturing system. They face a large system of many parts, where each part is complex in itself and where parts are interconnected in complex ways. This book addresses the ways maintenance specialists acquire and use information during troubleshooting and the types of difficulties they encounter in order to guide the improvement of computer-based troubleshooting support systems.