1) The N in PRND2L 
Double Overhead Camshaft: a DOHC engine has two camshafts in each cylinder head; one camshaft operates the intake valves, the other actuates the exhaust valves.
Dual Over Head Cams. Two camshafts found in the head or top of the engine that open and close the valves. Two cams allow more precise control than one.
Double Overhead Cam
Department of Health and Children