A long, thin metal wire is suspended from a fixed support and hangs vertically. Masses are suspended from its lower end. The load on the lower end is increased from zero and then decreased again back to zero. The diagram shows the force-extension graph produced. [Figure showing a force-extension graph. A curve starts from origin, goes up linearly to S, then curves further up to T, and then decreases along a path that returns to a non-zero extension R at zero force.] Where on the graph would the elastic limit be found?