From the abstract: "This report discusses the iterative guidance mode and its application to three-dimensional upper stage vacuum flight. It is an inertial or closed system mode in that the only inputs required after liftoff are available from the onboard navigation system. That is, the iterative scheme computes steering commands as a function of the state and of the vehicle - velocity, position, longitudinal acceleration, and gravitational acceleration - and the desired cutoff conditions. The guidance commands are updated each guidance cycle, using the updated state of the vehicle. The iterative guidance scheme is a path adaptive guidance scheme in that it will retain its optimization properties under all expected types and magnitudes of vehicle perturbations without any loss in accuracy at liftoff."