NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine.

Support for this project was provided by core funds of the Computer Science and Telecommunications Board. Core support for the CSTB is provided by its public and private sponsors: the Air Force Office of Scientific Research, Apple Computer, the Advanced Research Projects Agency, Digital Equipment Corporation, the Department of Energy, IBM Corporation, Intel Corporation, the National Aeronautics and Space Administration, the National Science Foundation, and the Office of Naval Research.

Library of Congress Catalog Card Number 94-66575

B-456