 Command entry:
Command entry: 
 Modify panel 

 Select a NURBS object. 

 Modifier stack display 

 Curve sub-object level 

 Select curve sub-object. 

 Curve Common rollout 

 Make COS button
            
 This dialog converts a curve to a point curve on surface or CV curve on surface.
         
         The Make COS button that displays it is enabled only for the following types of curves:
         
         If the curve is already a curve on surface, this dialog lets you change its type.
         
          
            Interface
            
  - CV Curve On Surface
- 
                   
                     Converts the curve to a CV curve on surface.
                      
 
- Number of CVs
- 
                   
                     Specifies the number of CVs in the new curve.
                      
 
- Point Curve On Surface
- 
                   
                     Converts the curve to a point curve on surface.
                      
 
- Number of Points
- 
                   
                     Specifies the number of points in the new curve.
                      
 
- Preview
- 
                   
                     When on, previews the effect of the conversion in viewports. Default=on.