In a 2006/7 series, entitled Column Structure I through Column Structure XII, the 12 canvases each have a central vertical trunk measuring 10 feet high and 2 feet wide that is subdivided by straight, horizontal lines and appended with squares or triangles that jut from the sides, usually near the top.
A series of twelve canvases, each with a central vertical trunk measuring 10 feet high and 2 feet wide, divided by straight horizontal lines and topped with squares or triangles protruding from the sides, are described in this passage.