I believe what they are talking about is any pump action marine toilet connected to a holding tank which can be pumped out at the dock. That involves an outlet on the side of the boat connected to a macerating pump
My boat has a toilet like this:
and it is connected to a sewage holding tank in the engine compartment. The toilet draws in fresh sea water for the flush (from a sea **** through the hull) and flushes into the holding tank. There is a sewage outlet at the back of the boat and a macerating pump pumps the sewage into the marina's main sewage tank when you dock.
