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.