The function of simulation in training is to provide a realistic operational experience by exposing trainees to the types of signals they will be expected to deal with under dangerous, real-world circumstances. Its principal value is to train the operator in a range of tasks that vary from simple 'knobology' (i.e., What knob does what?) to the sophisticated use of EW equipment in extremely stressful situations. A secondary use of operator-interface simulation is to evaluate the adequacy of the operator interface provided by a system. (Are the system's controls and displays adequate to allow the operator to do the job that must be done?).