I and a few others are designing yet another open instruction set architecture(ISA). Open ISA is thought by us as "free to see, and implement(even when selling it)". But we want to make this specification more than just "free", able to co-develop next versions in true open-source fashion(or just grant companies to make their own modified sets).
So we want to keep this under zlib license, highly permissive but still making the second developers to give credit for original developers. But is it possible to make just specification like ISA under a license?