There are two kinds of drop. A drop involves getting moving, then cutting off the car(s) behind the engine, the engine getting out of the way, and then car(s) rolling by. The difference between the two is that in a "drop", as we used to say on the SP, the engine gets out of the way by going one way at a switch while the car(s) go the other. With a "jackass drop", the engine has to stop and change directions to get out of the way, and this type of drop is obviously more tricky. The problem is that all the terms for "drop" vary from place to place and terminal to terminal on a railroad, not to mention between the railroads themselves. Since I've heard "dutch drop" all too often applied to either situation, I try to avoid using the term altogether.