SIMNET was the first successful implementation of large-scale, real-time, man-in-the-loop simulator networking for team training and mission rehearsal in military operations. The paper provides some historical background on how SIMNET was developed within the US Department of Defense, and outlines the key philosophical and architectural principles on which it was based. The SIMNET battlefield simulation was sponsored by ARPA (then called DARPA), in partnership with the US Army, and was developed and implemented between 1983 and 1990. The emphasis of SIMNET from the outset was on enhancing tactical team performance by providing commanders and troops an opportunity to practice their skills in a dynamic, free-play environment, in which battle outcomes depend on team coordination and individual initiative, rather than on scripted scenarios controlled by an instructor. This program demonstrated the feasibility of linking together hundreds or thousands of simulators (representing tanks, infantry fighting vehicles, helicopters, fired-wing aircraft, etc.) to create a consistent, virtual world in which all participants experience a coherent, logical sequence of events. In this world, the causal connections among these tactical events, from the individual crew station to the battalion command post, are clear and easily inspectable. The SIMNET architecture and protocols have evolved into the Distributed Interactive Simulation (DIS) Standard Protocols (IEEE 1278-1993 and its successors), and have provided the foundation for a new generation of battlefield simulations for training, mission rehearsal, tactics development, evaluation of hypothetical new battlefield systems, and concept testing and evaluation. The authors are two of the principal architects of SIMNET: Thorpe was the original DARPA SIMNET program manager and Miller formed and led the group at Bolt Beranek and Newman, Inc. (BBN) that designed and implemented the SIMNET protocols and software.>

This paper describes experiences gained during the course of a fairly large, multi-site project in which an integrated, computer-based electronic message and document preparation system was employed as the principal coordinating mechanism for the project. Approximately 60 individuals had direct access to this system and used it as their primary means of communication for the duration of the project.