Geographical Information Systems are becoming increasingly important to geologists, geographers, and urban and environmental planners, amongst others. Although there is an increasing number of such systems available on the market, many questions of a theoretical nature need to be addressed, because of the inherently large amounts of data and the lack of appropriate models and languages. Also, there is a need for flexible and efficient usage of GIS, thus permitting their application in a broad range of new areas, such as navigation systems for transport and the automotive industry. ESPRIT Working Groups provide a structure that enables researchers to meet, interact and share research results, thus providing a platform for ad dressing fertile research areas with significant industrial promise. This par ticular volume is the result of a workshop organised by the "Basic GOODS" Working Group. The challenge has been to define richer and more powerful data definition and manipulation languages, and also to develop new and efficient algorithms. The challenge has been met, as presented in this volume, and the Working Group has succeeded in laying a good foundation for future research and eventual applications. We look forward to seeing the results of the recently launched "AMUSING" project, which will build on this foundation.