The maximum zero fuel weight (MZFW) is the maximum weight allowed before usable fuel and other specified usable agents (engine injection fluid, and other consumable propulsion agents) are loaded in defined sections of the aircraft as limited by strength and airworthiness requirements.
The maximum zero-fuel capacity (MZFC) refers to the utmost load an aircraft can carry without fuel or certain essential fluids before takeoff, adhering to strength and safety regulations.