The other feature that this could refer to is the practice of employing what were effectively "cut outs" along the sides of the focsle, with the result that the upper deck was inset from the side of the ship by an increwasing degreee as you move aft. This was generally done to improve firing arcs for secondary guns mounted in casemates in the hull (or in the case of ships with wing turrets such as Dreadnought, to improve the arcs of part of the main battery).