There were circular loopholes, rhombic loopholes, loopholes shaped like a shogi piece, shinogi hazama (triangular loophole), hako hazama (box-shaped loophole), and so on according to the shape of windows, as well as ishisama (stone loophole used to fire a gun through the castle wall) that was cut in the top of a stone wall under a fence.
その窓の形により丸狭間・菱形狭間・将棋駒形狭間・鎬狭間・箱狭間などと呼ばれ、塀の下の石垣の最上部に切込みを入れるようにあけられた石狭間もあった。