Acceptable patent license for free software?

[MJ Ray]

Simon Josefsson <simon at josefsson.org> wrote:
> Hi!  I'm writing guidelines for IETF document authors on how to achieve
> free software compatible copyright and patent licenses [1].  [...]
> [1] http://josefsson.org/bcp78broken/draft-josefsson-free-standards-howto.html
> Does anyone have some references to any patent license that have been
> deemed acceptable to some free software projects?
>
> Going further, is there some kind of patent license that free software
> would _prefer_ (as opposed to just _accept_)?

Thank you for writing guidelines.  I cannot answer the above two
questions.  I am mostly ignorant of software patent licensing because
I believe pure software is a sequence of mathematical expressions
which cannot be invented, only discovered.

> To give a concrete example of what I'm thinking of:
>
> There is one patent license in <https://datatracker.ietf.org/ipr/942/>:
>
>   Subject to the terms and conditions of this License, Google hereby
>   grants to You a perpetual, worldwide, non-exclusive, no-charge,
>   royalty-free, irrevocable (except as stated in this License) patent
>   license for patents necessarily infringed by implementation (in whole
>   or in part) of this specification. If You institute patent litigation
>   against any entity (including a cross-claim or counterclaim in a
>   lawsuit) alleging that the implementation of the specification
>   constitutes direct or contributory patent infringement, then any
>   patent licenses for the specification granted to You under this
>   License shall terminate as of the date such litigation is filed.
>
> This patent license is a reciprocal license, but is fairly limited in
> scope.
>
> Would that be acceptable to free software projects?

No, I think - to call it free software, I would want to be able to use
the patent-covered software "for any purpose" and not just
"implementation of this specification" like in the above.  Compare
with http://www.fsf.org/licensing/essays/free-sw.html

Hope that explains,
-- 
MJ Ray (slef)
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