Late reply but it frustrates me when these examples are all (1) public standarda, or (2) two companies in bed with each other. The best counter-example I can t

Late reply but it frustrates me when these examples are all (1) public standarda, or (2) two companies in bed with each other. The best counter-example I can think of is "Microsoft NWLink", which was a Netware 3-compatible file server offered with Windows NT. How long and under which legal threats is unknown to me.