This volume, the eighth of a continuing series on information systems science, presents five timely topics which are of current interest in this growing field. In each chapter, an attempt is made to familiarize the reader with some basic background information on the advances discussed, so that this volume may be used independently or in conjunction with the previous volumes. The emphasis in this volume is centered upon file or­ ganization and performance evaluation, computational semantics, digital control, clustering analysis, and geometric modeling. Chapter I presents a comprehensive survey of file organization. In this chapter, Gudes and Ganesh discuss performance evaluation, imple­ mentation considerations, relationship to database models, and performance tradeoffs of various file organizations. The semantics of programming languages was discussed in Volume 2 of this series. This topic is revisited by Culik II and Farah from a different point of view. Chapter 2 is concerned with linked forest manipulation and models for formal description of a programming language. Linked trees reveal syntactical properties of a programming language and provide data structures for describing com­ putational semantics.