[kale]

I deal routinely with use patents in the medical field. There's a chemical that's been in use for 30+ years to stabilize polymers from ionizing radiation. It's used in practically all gallon milk jugs to protect them from UV degradation. A company has a bright idea in 2006 that this chemical would also stabilize medical device plastics during sterilization (usually gamma radiation), and get a use patent on this stabilizer for use in the medical industry. 30+ year old technology, used in several fields, but requires licensing to use it in medical devices. And this is a world patent.

I'm guessing the patent would be a use patent. The patent is on a specific use of the math (although it doesn't sound all that specific from the claims that I've seen).