A method of stoping in which the walls and back of the excavation are supported by a system of interlocking framed timbers (square set). A square set of timber consists of a vertical post and two horizontal members set at mutually right angles. The mining process is slow and only enough ore is excavated to provide room for installation of each successive set of timber. The stopes are usually mined out in floors or horizontal panels, and the sets of each successive floor are framed into the top of the preceding floor.