I think you mean DMP.... this lever sets the 3pt controls between Draft, Mixed and Position control. on Draft it adjusts the 3pt height based on how hard is pushed against the top link bracket (drive through a hole with the rear wheel so it sinks, the plough or cultivator ducks down and pushes the top link so the 3pt is automatically lifted)
its great for ploughing with 1 or 2 furrow ploughs, or cultivating with a cultivator with depth wheels or a roller at the back. With 3 furrows or more, the system with lower link arm sensing works better.
Dont use D or M setting when attaching implements, you might get hurt if the 3pt lifts because the top link sensor is actuated.