Product documentation and schematics
First hint "never divulge all of the details in a patent".
Thankfully nobody told HP that in the early 70's. The patents for the
98x0 series read like service manuals with schematics and ROM source
listings (the one of the 9830 is something like 900 pages long). The
info doesn't quite apply to production machines, but it's a heck of a lot
better than nothing!
Actually I know when we applied for patents and provided details of a
product we deliberately left out some key nuances and facts so that
somebody else could not totally reengineer the product from the details.
As I understnad patent law (and IANAL), if somebody 'competent in the
field' can't recreate the invention from the patent, then the patent is
invalid. Of course this would probably involve a long and expensive court
case, but anyway.
-tony