Ah ok, now I get it :) Nearly... :S

NURBS objects have 2 kinds of points, one kind that can be added along the edge of a patch, and one kind that is the corner of a patch, right?

So it works like bezier patches, just with more advanced edge curves (and different interpolation)?

Do you know anywhere where I can read about the fundamental methematical structure of NURBS? So I can understand how it's handled and interpreted mathematically. Just the concepts, not something where I have to understand some advanced math formulas. Haven't had advanced math for a few years now :)