Training device effectiveness is largely dependent upon the characteristics of the instructional subsystem. In most trainers, this includes the instructor, the instructional software, and above all, the interfaces (both hardware and software) to the other training device subsystems. The primary interface, the trainer IOS, must be designed and supported so that the training device meets not only the training objectives, but also the user requirements. Effective design can only be achieved through identification and understanding of the characteristics of the user and the required training, and then by ensuring that these data are reflected in the design of the station. The design task also requires detailed monitoring of the design effort to ensure that the necessary data are available and input to the design effort. The objective of the guide was, therefore, to identify the tasks involved and the data required during the major training device life cycle events which impact the characteristics of trainer instructor/operator stations. The guide focuses on "what" to do in design, not "how" to do it. A guide which focused on "how" it should be done would soon be outdated since hardware and software technologies are evolving so rapidly.