This document discusses different types of aircraft toilet systems, including removable toilets, liquid flush toilets, and vacuum toilets. Removable toilets are the simplest type, found on small aircraft, and involve removing the entire toilet unit when full. Liquid flush toilets are more common, using a waste collection tank and disinfecting chemicals. Vacuum toilets are also dry systems that use suction pipes and a centralized waste tank. The document provides details on the components, operation, servicing, and ventilation of these various aircraft lavatory systems.