Apple Shake 4 - Manual (Page 525)

Chapter 18 Compositing With the MultiPlane Node 525
Copy/Delete
These buttons let you duplicate or delete the currently selected renderCamera.
Link
The link button at the right lets you link the camera in the currently open MultiPlane
node to an animated camera within another.
Delete Cloud
Deletes a point cloud, but leaves the camera angle intact. This is useful if you plan on
redoing the track and you want to clear the old point cloud in preparation for
importing a new one.