The projection of any curve onto a surface will result in a cubic spline entity; regardless of the entity type of the curve projected.

Dialog Options:

Surface Offset Value

Specify a value for the Surface Offset.

Projection Method

Select either Normal to Surface or Skewed (Specify Direction) for the Projection Method.

Trim Projected Curve to Boundaries

When this setting is checked, the projected curve will be trimmed to the boundaries of the surface. If the projection falls off the edge of the surface, it will be projected onto the theoretical linear tangential extension of the surface.