Both a type and position of architectural molding. Picture rail molding resides below a cornice or crown molding and above a chair molding. On a ten foot tall wall the picture molding would typically be placed between eight and nine feet from the floor. Picture rail molding is so named as it used to function as a place from which the cables, ropes or sashes supporting a picture frame would hang. http://www.govart.com/hardware_rail_hooks_A.html The above picture shows a picture rail and picture hanger--the proper way to hang a picture without putting holes in the wall.