SpaceX: just optimal control or something else?

SpaceX uses a particular set of control laws, called Guidance for Fuel Optimal Large Divert (G-FOLD). This is an algorithm that is developed to compute, onboard in real-time, fuel optimal trajectories for large divert maneuvers necessary for planetary pinpoint or precision landing. It uses loseless convexification for converging into a globally optimal solution that incorporates all relevant mission constraints. But, what does it mean?

Credit: SpaceX