Apple Shake 4 - Manual (Page 308)

308 Chapter 10 Parameter Animation and the Curve Editor
When the Interleave mode is set, the selected keyframes jump over the adjacent non-
selected keyframes to the next segment of the curve.
Push
When the Push mode is set, the selected keyframes push the other keyframes along
the curve. In the following example, the selected keyframes are pushed to the left of
the Curve Editor. Therefore, keyframe A pushes keyframes 1 and 2, as well as all other
keyframes to the left of keyframe 1.
Replace