A standard "dish" piston is exactly that, the WHOLE top is just a dish shape and round. Inverted dome, reverse dome, stepped dish whatever you want to call it refers to pistons pictured here. Why? because if you had a regular DOME piston to make big compression, it would be contoured to fit inside the chamber. These are inverted or reversed in order to lower compression and still have a quench pad.

I can show you plenty of "dished" pistons.........the ones above are NOT them