RC inpuit - Newbie question

I looked at the specs for the PIxhawk and it shows a 3 pin input with +, - and signal for RC. Obviously it is a composite input and I have already figured out that the lines labelled SBUS are for SBUS out. What the specs dont tell me is if RC input can be used for CPPM or if it is for SBUS. The literature says that the Pixhawk supports both sum PPM and SBUS but again I am unclear what goes where.

Your receiver should be connected into the three pins on the left. I think you alreadyfigured that one out. Right?