The control-point SVG value specifies a set of four values: x1 y1 x2 y2, describing the Bézier control points for one time segment.
The keyTimes values that define the associated segment are the Bézier "anchor points", and the keySplines values are the control points. Thus, there must be one fewer sets of control points than there are keyTimes.
<control-point> = <number> ,? <number> ,? <number> ,? <number>