NURBS surface objects are the basis of NURBS models. The initial surface you create using the Create panel is a planar segment with points or CVs. It is meant simply to be "raw material" for creating a NURBS model. Once you have created the initial surface, you can modify it on the Modify panel by moving CVs or NURBS points, attaching other objects, creating sub-objects, and so on.
There are two kinds of NURBS surfaces:
You can also create a NURBS surface from a geometric primitive.
NURBS surfaces can contain multiple sub-objects, including NURBS points, NURBS curves, and other NURBS surfaces. These sub-objects are either dependent or independent.
Creating and Editing Point Sub-Objects
Editing Surface CV Sub-Objects
You can also create NURBS surface sub-objects by objects.
Both NURBS curves and NURBS surfaces have a Display area in the General rollout on the Modify panel. These controls affect which portions of the NURBS geometry are displayed. Next to the Display area is the button that turns on the toolbox for creating sub-objects.
Display Controls for NURBS Models
You can use MAXScript to control NURBS objects. See "Working with NURBS in MAXScript" in the MAXScript help file. Choose Help Additional Help, and then choose MAXScript from the list of additional help files.
Point surfaces are NURBS surfaces whose points are constrained to lie on the surface.
A CV surface is a NURBS surface that you control by manipulating control vertices (CVs). The CVs don't lie on the surface, but instead define a control lattice that encloses the surface. Each CV has a weight you can adjust to change the shape of the surface.