Notice that, though the actual value of the second keyframe is 0, the value of the resulting spline is 0.33 due to the unique smoothing and weighing algorhythms of a BSpline. The weight can be modified by left clicking on the keyframe to select it, holding down w as well as the left mouse button and moving the mouse to the left to lower the tension and to the right to increase the tension. This also can be done with multiple selected keyframes simultaneously.