"To me that stuff is implied with copyleft, because how else could it work?" The "copy" in Copyleft gives you your answer - it ought to be about sharing copyri

"To me that stuff is implied with copyleft, because how else could it work?" The "copy" in Copyleft gives you your answer - it ought to be about sharing copyrights to code, not patents. You don't have to grab patents (which expire in twenty years.) Copypatentleft is what we really have, instead, with GPL, and that's a whole different beast. So, it is of course logically possible to confer the copyright to code that exploits a patented idea without conferring the patent rights at the same time. That would mean that not everyone could use some shared code, without a license, even though they have a copyright license and can share and examine it. The patent holder would retain their patent rights. Why respect patent rights? Because the majority of value in American businesses is IP - trade secrets and patents being the bulk of that. GPL is therefore a non-starter in the corporate world, more often that not. You don't have to share patents. If you insist, then your code gets duplicated under another "more permissive" open software license at enormous expense, that's all. If you want my work on your community code, great! If you want my ideas - my patented ideas, um, no.