Single
Create splines on a surface through a point that is the projection of a point you will choose. That projection can be either normal to the surface or parallel to the construction view.
Increment Length
Create splines a specified distance apart (starting along the edge farthest from the surface arrow).
Number Of Splines
Create a number of evenly spaced splines (including along the surface edges).
Edges
Create splines along the surface edges.
Knot Lines
Create splines at the natural knots of the surface.