[Harmony-Drafting] copyleft outbound licensing

[Allison Randal]

Mentioned in the meeting minutes, carried on here for further discussion.

We've talked a lot about how to handle copyleft licenses in the outbound
license section. All the current options include copyleft licenses, but
the discussion has ranged over whether we can draft an option that
covers all copyleft licenses and only copyleft licenses. We added Option
Four as an attempt at that, but later discovered that the FSF also
recommends permissive licenses. One proposal was an option for "any
copyleft license", with a suggestion that copyleft is well enough
understood to need no definition. But, the following discussion
indicated that there were many different understandings of what copyleft
means, and that how to define copyleft in a sufficiently
broad-but-narrow and future-proof fashion is less than obvious.

I had a conversation with Bradley Kuhn this week, where he pointed out
that generically defining copyleft licenses isn't useful, because for
the copyleft philosophy there's a huge difference between GPL, LGPL and
AGPL, and projects make very intentional choices on those distinctions.

My proposal, based on Bradley's comments, is that we drop Option Four,
and in our usage guide explain that the best way to capture "only
copyleft licenses" is Option Two with an explicit list of the copyleft
licenses the project supports.

Comments?

Allison