Skaters were required to trace these circles using one foot at a time, demonstrating their mastery of control, balance, flow, and edge to execute accurate and clean tracings on the ice. The compulsory figures used by the International Skating Union (ISU) in 1897 for international competitions consisted of "two or three tangent circles with one, one and a half, or two full circles skated on each foot, in some with turns or loops included on the circles". The patterns skaters left on the ice, rather than the shapes the body made executing them, became the focus of artistic expression in figure skating up until the 1930s. Each figure had its own technique skaters had to master while executing geometrically perfect circles, and each figure's name reflected that technique.