> (er, surely it's the other way around? the 3-clause one is OSI approved and the 4-clause one is not)

Whoops, I did indeed type that a bit too quickly.

> Having a separate software license + secondary patent grant license is very very common

Perhaps, but those are separate. In this instance it was one and the same license, with any violation of the patent part terminating the whole license - including the non-patented software parts.

Additionally, the AOMedia patent license seems to be a bit different: the OrioleDB one said it would terminate when you sued Supabase (and to make it worse: sue them for any reason), but the AOMedia one says it'll terminate if you sue anyone over the licensed patents.

In other words: the OrioleDB one protected only Supabase, the AOMedia one protects the entire community. When it comes to being compatible with open source licenses, details like that become crucial.

I like how well-thought-out the licence revocation clause of the AOMedia patent licence is. It takes effect when a licensee sues over an implementation specifically over the relevant patent claims--so lawsuits unrelated to these patent claims are allowed (so if you infringe on other patents but also implement the licensed patent in the same implementation, the rights holder of the other patents can sue you over those claims without losing their licence)--and there is also a carve-out for counterclaims, and lawsuits to enforce this licence.

But I am not sure if the first exemption is necessarily a good thing. The Apache License, Version 2.0 is broader in what may be grounds for patent licence termination. So it is a better deterrent against patent trolls (even if that means some legitimate patent claims are also discouraged).