Creates curves-on-surface at the intersections between existing surfaces.
On First Surface – Create curves-on-surface on the target surfaces, but not on the intersecting surface(s) you selected.
On Both Surfaces – Create curves-on-surface on the target and the intersecting surfaces.
Save the history of the projection for later editing. If you turn Create History on, you can modify the surfaces that were used to create the projected curves, and the projected curves will update.