Doughnuts appear in a number of mathematically classifiable forms,
predominantly oblate spheroids and ellipsoids, cylinders with domed
ends, and toroids.

The logical progression is to label them not as "ring" or "filled" but by
the set of equations that describes their form.

This would be
immensely satisfying to mathematicians, physicists,
engineers and geeks of all sorts, as questions such as "Do I
get more
sugar dusting on a small torus or a larger spheroid ?" can be
unambiguously resolved before approaching the counter.

Not really relevanthttp://picasaweb.go...vtA?feat=directlink Spotted in a local bakery window, I think I posted this image before [pocmloc, Apr 02 2014]

The sugar-dusting answer is obvious. You need a
Sierpinski donut fractal with infinite surface area but
zero
volume. Infinite amount of sugar dusting but zero
calories.