Apple Shake 4 - Manual (Page 317)

Chapter 10 Parameter Animation and the Curve Editor 317
In addition, the keyframes completely define the curve, so there is no tangent control
whatsoever.
Cardinal Splines
CSpline(cycle, value@key1,value@key2,...value@keyN)
CSplineV(time_value, cycle, value@key1,value@key2,...value@keyN)
Cardinal splines trade off curvature continuity for local control. When a keyframe
moves, only four segments are affected (two before and two after the keyframe). In
addition, for any keyframe, tangents are automatically computed to be parallel to the
segment joining the previous keyframe and the next keyframe. They are the
programmer’s best friend because they are so simple to evaluate—only two points are
needed, which simplifies data management (no tangent or other complicated stuff ).
Jeffress Splines
JSpline(cycle, value@key1,value@key2,...value@keyN)
JSplineV(time_value, cycle, value@key1,value@key2,...value@keyN)