MS-PL/GPL compatibility, was Re: For Approval: Microsoft Permissive License

Wilson, Andrew andrew.wilson at
Thu Aug 23 18:47:54 UTC 2007

Alexander Terekhov wrote: 

> Andrew Wilson wrote:
>> Actually, Tobia, your original position is correct (at least it
>> is consistent with most people's reading of GPL, and other copyleft
>> licenses such as EPL ...
... long excerpt from Eclipse FAQ follows ...

Alexander, the case under discussion here is what license
applies to a derivative work which includes source code
licensed under MS-PL combined with source code
under a copyleft license to create a derivative work.

I'm certainly well aware EPL permits modules to be combined
with non-EPL modules and the whole licensed under a different,
even a proprietary license.  On the other hand, in the case
under discussion, when you create a derivative of EPL source
code you have created a capital-C Contribution, and EPL
is quite clear that capital-C Contributions 
"must be made available under this Agreement" (sec. 3 para 2 (a)).
This is in contradiction with the equivalent provision
of MS-PL which mandates MS-PL licensing for derivatives, and we have
certainly appears to be a conflict of licenses.  
As noted in my original posting,
the same analysis applies to the other most commonly
used copyleft licenses, all of which equally immiscible
at the source level with MS-PL (although they may linkable
at the module or plug-in level, as would separate modules
of EPL and MS-PL code).

In John Cowan's "MS-PL FQA (frequently questioned answers)"
my version of his number #3 would read as follows:

3) Can I create a larger work which, as a whole, is under some other
   license (but not a copyleft license, e.g. GPL, EPL, or CDDL),
   and includes a portion under the MS-PL?

   Definitely.  It's a derivative work, and the MS-PL says you can make
   those freely, and the Copyright Act says you can license them however
   you like, provided your making the derivative work in the first place
   was lawful.

Now, back on the (real) topic, approval of the licenses.
Unless and until there is an OSD #11 which actually requires
compatibility with other open source licenses, I do not believe
OSI can reject a submission solely on the grounds of incompatibility.
And, MS-PL is non-duplicative, since as previously noted, other
approved "permissive" licenses do not have its "license stickiness"

Andy Wilson
Intel open source technology center


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