Pulling V.A at idle

Man, Y'all are awesome! My "Mr. Technical" *** over thinks things. So I was Assuming it HAD to be Exactly True TDC. I get it now! So the height don't mean squat, BUT the actual travel of the piston up, and Down, hitting stop,from Crank Throw Center, allows me to make 2 separate Reference Points, one BTDC and One ATDC, then split the difference? So the amount of throw is nothing, it's Crank Throw center, for lack of better terms?