BSD and MIT license "compliance" with the MS-PL

Chuck Swiger chuck at
Fri Apr 17 19:02:31 UTC 2009

On Apr 17, 2009, at 11:40 AM, Wilson, Andrew wrote:
>> Where is it categorized as copyleft (besides the FSF list)?
> MS-PL was categorized as copyleft during the discussions on
> OSI approval.  That was actually one of the key arguments in
> favor of approval, since a weak copyleft, permissive license
> is non-duplicative of BSD/MIT/Apache et al.

Agreed.  While I don't see a large uptake of projects using the MS-PL,  
the license is well-crafted.

> Were it not read as weak copyleft, I doubt it would have been  
> approved.

It's clearly OSD-compliant and was approvable from that standpoint; as  
for license-proliferation concerns, well, I don't think that adding  
more variants of permissive licenses to the OSI list of approved  
licenses is a significant problem, although it doesn't seem to be  
helpful, either.  I might wish that people spent more effort trying to  
innovate with code rather than with writing new licenses....

> Certainly, the intent of 3(D) appears to be that MS-PL applies to  
> any source derivatives of an original MS-PL work
> (and thus such derivatives could not, for example, be GPL'd).
> Back on the original topic, I don't see any reason to believe
> BSD or MIT code could not be combined with MS-PL code.

Also agreed.  From the original submission thread of the MS-PL  
license, by Jon Rosenberg of Microsoft:

"* Can MS-PL code be redistributed in combination with other code
that is licensed under a different license?

As long as the original MS-PL licensed code is redistributed under
the MS-PL license, then the MS-PL places no restrictions on
combining MS-PL code with other code that is licensed under another
license.  Licenses that prohibit the distribution of code under any
terms other than the terms of that license will not be compatible
with the MS-PL."

I think this makes it clear that the MS-PL is fully compatible with (a  
phrase that seems more sensible to use here than "compliant with")  
other permissive licenses such as the BSD and MIT licenses, and that  
this was intended, not accidental.


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