[Radio Wrangler]

I would expect the patents on Dolby B and C to have expired a long time ago. The only thing Dolby can licence is the use of the name. So someone could make a compatible system even an exact replica, they'd just have to pick their own name.

The whole purpose of patents is to bring inventions out into the public domain. The patent period is a reward, by giving the inventor an open playing field for a limited number of years. In contrast, registered trade marks last as long as someone keeps paying the fees.

David