Pistons specs question for 340 build

If a piston has a negative piston head volume figure, that means whatever that volume is REMOVES total chamber volume. That's how domes are measured, with NEGATIVE volume. That's why when looking at a domed piston, or a piston whose head has a positive deck height its figure is written as a negative number. It should be figured into a compression calculator as a negative number, since it REMOVES total chamber volume through the displacement of the piston head into the chamber. When looking at flat tops with valve reliefs, or dishes, they will have a positive number, since their piston heads ADD TO the total chamber volume.