The four-room house is so named because its floor plan is divided into four sections, although not all four are proper rooms, one often being an unroofed courtyard. It is also sometimes called a pillared house because two--or all three--of the parallel ground-level "rooms" are separated by one--or two, respectively--rows of wooden pillars. The pillars, however, are not the defining feature of the four-room house, and this error of terminology leads to the confusion of four-room houses with other buildings, such as storehouses and stables, where pillars were widely used, but which were not constructed under the four-room house layout.