Yes, but nothing in your answer actually justifies why the locking mechanism needs to be so complicated. As the previous poster rightly pointed out, airplanes are also not slinging shit overboard at Mach 0.8, and they manage with a perfectly simple sliding mechanism. Or, staying with modern trains, the French TGVs also don't have such an over-engineered solution.. Although, agreed, they don't have on board nuclear reactors to prenuke their toilet waste.. That might warrant a 3 button system with voice control..