question : MFnNurbsSurface

[matthew]

Hello there, 

In MFnNurbsSurface, 

I saw "The U and V knot vectors for NURBS surfaces are of size (spansInU + 2*degreeInU -1) and (spansInV + 2*degreeInV -1)"

and I wonder what these vectors are for. When I tested with a nurbsplane created by cmds.nurbsPlane( w=1, lr=10, d=3, u=1, v=10, ch=0), 

I got the scalar values U=6 and V=15. what do these numbers refer to?

Thanks for any help!

M