This option will display the control point locations for the spline with a polyline connecting them. You can select and drag these control locations similar to the fit points above. As you drag a control location, other nearby fit and control locations may move as well.

When the control points are moved, the fit points are constrained to their current parametric locations on the spline, but the spline will not be re-fit through the fit points in this option. This option can be used for finer control of the curve than direct movement of the fit locations.

Note that if you have manually applied "Fixed" constraints to all or most of the Fit Points, or if there are a large number of constraints and dimensions on the spline which severely restrict changes to the shape of the spline, in some cases this option will behave unpredictably. If so, you can use "Undo" to back out the change, then remove some of the constraints before trying again.