Apple Shake 4 - Manual (Page 318)

318 Chapter 10 Parameter Animation and the Curve Editor
Jeffress splines are similar to CSplines, except they are guaranteed to never overshoot.
If two keyframes have the same Y value, a flat segment connects them. This is very nice
for animation, since you have a good idea of your limits.
Hermite Splines
Hermite(cycle,(value,tangent1,tangent2)@key1,...
(value,tangent1,tangent2)@keyN)
HermiteV(time_value,cycle,(value,tangent1,tangent2)@key1,..
(value,tangent1,tangent2)@keyN)
Hermite splines also give up on trying to produce curvature continuity, but they add
tangent controls (so the animation is likely to look bad unless you eyeball the
smoothness each time you move stuff around). You also have the ability to break the
tangents (Control-click the handle end in the Curve Editor). It takes some effort to get
right, but you can shape it the way you want.