How to describe the acceptable terms to receive documentation?

I would start with what we want to achieve. We need that the documentation is complete and accurate, this is a technical requirement. We need that the documentation be readable, therefore needs to be in an open format that anyone has the permission to build something to read and modify (sorry to belatedly bring this up). We need that the documentation is free from restrictions that would limits its circulation, including by requiring seeking additional permission or requiring royalties or requiring audited distribution or the likes.

The scope of the license is therefore quite limited, and I agree that CC-BY and CC-zero would qualify. CC-BY-SA would also qualify. NC and ND would not qualify. BY would also require that there are no DRMs or other technical restrictions, but as long as they are not imposed technically, I don’t see this as a requirement.

For the time being I do not see the need to be ultra-specific of what open means. While the requirements above seem all relevant, there might be other. Do we need to vet those licenses? I would regard this as a good service that OSI could implement to remove any doubts, but at the same time I would not put it as a hard requirement.

[sorry for the bad English, I am pressed to complete other things and can’t re-edit much]