D= draft control , for heavier soil acting implements, main lever is either up or down with the lower half of its travel being the weight transfer and depth control
M= mixed draft and position, for light soil acting implements whose depth is directly controlled by the position main lift lever, but is also affected by the movement of the top link.
P= position control, height of the arms is directly proportional to the position of the lift lever with no contribution from the top link.