[Read Spline]: Read Z values from reference spline.

[Update Spline]: Write Z values to reference spline.

[flatten]: Set seletect points to the same value of first point. Right mouse button set to last point.

[Lerp]: Linear interpolation for selected points.

[Export CSV]: Export current spline to a text file with 3 columns (pointID elevation distance).

[Import CSV]: Import text file with 2 columns (pointID elevation).