Hi! I'm writing guidelines for IETF document authors on how to achieve free software compatible copyright and patent licenses [1]. The copyright area is rather well understood, I think; pick any liberal license that is compatible with all (reasonable) free software licenses and you are done.
However, the patent license area seems less clear to me.
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_)?
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?
/Simon
[1] http://josefsson.org/bcp78broken/draft-josefsson-free-standards-howto.html