You
            can reset a keyframe after its tangent handle has been moved in
            the Animation Curve window. You can also reset a split tangent handle.
         
         NoteTangent handles appear
               only on animation curves that have Hermite or Natural interpolation.
               See 
                        Setting Interpolation.
            
 
         To reset a tangent handle in Auto mode:
         
         
            - Access the Animation Curve window.
            
- From the Edit Mode box, select Auto.
            
- Click the tangent handle.
               It resets to its default
                  value. The slope of the animation curve is updated automatically.
                
To reset a tangent handle in Move mode:
         
         
            - Access the Animation Curve window.
            
- From the Edit Mode box, select Move.
            
- In the Channel Editor, Alt-click a tangent handle.
               It is reset to its horizontal
                  position.
                
To reset a split tangent handle:
         
         
            - Access the Animation Curve window.
            
- Select one or more keyframes with split
               tangent handles.
            
- Click Reset Chn.
               The selected keyframes'
                  tangent handles are reset.