With the Edit Keyframes tool (above the parameter list) selected, you can also perform advanced keyframe modifications. You can reverse keyframes to invert the corresponding animated effect without re-animating it, lock keyframes (individually or in groups) to prevent accidental adjustment, or disable an entire curve to suspend animation for that parameter.
In the graph area Keyframe Editor, drag a selection rectangle in the graph to select the keyframes to reverse.
Control-click a selected keyframe, then choose Reverse Keyframes from the shortcut menu.
The keyframes are reversed.
In the Keyframe Editor, select the keyframes to lock, then control-click one of the keyframes in the graph and choose Lock from the shortcut menu.
Locking prevents further modification the keyframes. (You can also lock all keyframes in the Keyframe Editor by selecting “Lock keyframes in time in Keyframe Editor” in the Time pane of Motion Preferences.)
In the Keyframe Editor, select the keyframes to disable, then Control-click a keyframe in the graph and choose Disable from the shortcut menu.
Disabled keyframes are ignored and have no effect on the object’s animation. If you disable a keyframe, the curve readjusts itself as if that keyframe didn’t exist, even though the keyframe is present in the Keyframe Editor, in a dimmed state.