I was gonna say "1999? That's awfully late for a subdivision modification patent. Sub-D modeling was already popular at that time." Besides, one can sidestep s

I was gonna say "1999? That's awfully late for a subdivision modification patent. Sub-D modeling was already popular at that time." Besides, one can sidestep such a patent through a surface definition transform: got polys? convert to a parameterized representation and then re-tesselate to the desired sub-d form.