Enter an option [Setvars Crtallv eXitl:
Setvars - Sets parameters for constructing directing B-curves.
Crtallv - Constructs directing B-curves of the B-surface and moves to GD of the form 'framework of directing B-curves on a network of S-polygons (V_3D_Frame)'
Delallu - Removes the frame of forming B-curves and returns to GD 'polygonal mesh (3D_Mesh)' .
Exit - Exit.