Good question, navigating around the US patent office site isn't easy. The index to the classifications is here
http://www.uspto.gov/go/classification/uspcindex/indextouspc.htmyou may need to download a viewer to see the images, there is some information here
http://patft.uspto.gov/help/images.htm#reqit is kind of interesting the stuff you can find out, about a year or so ago, I bought a leg-of-mutton case, the only markings on it were a patent date. By researching the patent, I found
that it was issued to the Hoover company, that before they made vacuum cleaners they made leather goods.
