Cinema 4D Program Documentation Reference Cinema 4D Basic Features Spline Menu
Function available in CINEMA 4D Prime, Visualize, Broadcast, Studio & BodyPaint 3D

Equal Tangent Length

For each selected point, the shorter tangent handle is set to the same length as its partner tangent. If no points are selected, all points are automatically included in the action.

Before.
After.

This command can be applied to Bezier Splines only. All other types of spline have preset interpolation which cannot be changed.