I think he was alluding to a dial-in dump limit. I can recall a Spam driver (not sure what type) being slightly bemused at a system being designed in such a way. He explained that, in his jet, you worked out a min fuel level you wanted for the trip and dialled it in when you got to the jet. If you dumped fuel, it dumped down to that level and automatically stopped - rather than being hardwired at an arbitrary level.