Getting way offtopic here and splitting hairs but..
Suntour's slant-parallelogram design was a patent, not a trademark.

US Patent 3,364,762 - SunTour Gran-Prix

Designs and "inventions" are patented for protection. The company or person that patents something has the exclusive right to use or license out the design to others for a set period of time. Tradenames and likenesses are trademarked for protection. Suntour could have trademarked the name Sunshift3 or something like that and called their patented slant-parallelogram design that as a tradename if they wanted. The actual design would be protected by a patent, the Sunshift3 name protected by trademark. After the slant-parallelogram design patent expired in 1984, others could freely (and did) copy it (at will with no money going to Suntour) but they could never call it the mythical Sunshift3 without Suntour permission because that would have been a trademarked name (trademarks do not automatically expire on some future predetermined date).

Shimano has a trademark on "SIS Index" and the logo, no one else can use that name or logo, it does not apply to an actual shifting process or mechanism, it is just a name that Shimano can apply to anything they want. Other companies can make indexing shifters but they can't call them SIS Index shifters. Shimano could call a hub an "SIS Index" hub if they wanted to.

http://www.trademarkia.com/sis-index-78202182.html

Notice the trademark request makes absolutely no mention at all about a shifting process, indexing, gears, or any methods at all. The trademark only describes the name "SiS Index" and the logo.


I know this has nothing to do with the OP question.