Project geometry from another sketch onto the active sketch plane.
Reference geometry can be edges and vertices, loops, work features, or sketch geometry. You can also use projected geometry to:
The size and position of projected geometry is fixed relative to the originating sketch ( reference geometry ). You can constrain sketch geometry to the projected geometry.
The projected geometry is associative, and moves or changes when its parent sketch moves or changes. Sketch geometry that is constrained to the projected geometry also moves.
When you project spline curves from the construction environment to a 2D sketch, you create nonassociative reference splines. Any edits to a reference spline create an approximation of the original spline, which can cause the loss of accuracy of the curve.
You can break the link, and then use any sketch or constraint command to edit normal style geometry.