Rhino 3D: Insert Knot comand under Control Points

Part of the information needed to define a NURBS curve is a list of numbers called a knot vector and the values of the numbers in this list are called knots.(http://docs.mcneel.com/rhino/5/help/en-us/commands/insertknot.htm)

Insert Knot command allows me to add knots on curves or surfaces. If a knot is added to a surface, an isoparametric curve (a curve of constant u- or v-value on a surface) will display on that surface. Then I will have to use Toggle option under InsertKnot to determine the direction of the curve between u and v.

Rhino 3D - Rebuild command

In Rhino 3D, Rebuild under Edit menu is pretty powerful tool to subdivide a surface. Don't forget!

By McNeel Associates, the developer of Rhino, the Rebuild command "reconstructs selected curves or surfaces to a specified degree and control point number."(http://docs.mcneel.com/rhino/5/help/en-us/commands/rebuild.htm)