Allows you to pick curves-on-surface.
Curves-on-surface are special curves that exist on surfaces. They are used to mark out which parts of a surface to trim.
Usually, you create curves-on-surface by intersecting or projecting other geometry onto a surface. You do not normally need to edit curves-on-surface by hand.
Another type of curve-on-surface is a visual curve, produced by tools such as Cross Section Editor, Parting Line, Highlights, and so on. These curves are for display purposes only, and have no geometry attached to them.
Left: Geometry curves-on-surface. Right: Visual curves-on-surface.
To pick a curve-on-surface, choose Pick > Object Types > Curve on Surface 
and click the curve-on-surface. Visual curves-on-surface can be picked independently from geometry curves-on-surface, using the options below.
Procedures
Pick Curve on Surface Options
- Visual
- Check this box if you want the tool to pick visual curves-on-surface.
- Geometry
- Check this box if you want the tool to pick geometry curves-on-surface.