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

Tzeng, Nigel H. Nigel.Tzeng at
Fri Apr 17 15:58:04 UTC 2009

>From: Matthew Flaschen [mailto:matthew.flaschen at] 
>Tzeng, Nigel H. wrote:
>> Given that MS-PL is itself a weak copyleft it would be an absurd
>> position but not for the reasons you imply.  Logic based on false 
>> premise can lead you merrily along some absurd paths.

>MS-PL is viral (I use this in the neutral sense).  But it's not even a
>weak copyleft (which is something like MPL or MS-RecL).  Copyleft
>licenses require that source code is provided when binaries are
>provided.  MS-PL has no such requirement.

Mmmm...I believe that MPL requires source release only if modifications are made.  I may be incorrect since I don't contribute to any MPL projects or use the license myself so I don't know for sure.  You'll have to point out the relevant sections out to me but my cursory reading of Section 3.2 and 3.6 indicates that source must be made available only for modified code.

In any case, the FSF calls the MS-PL a copyleft license:

Microsoft Public License (Ms-PL) 

This is a free software license; it has a copyleft that is not strong, but incompatible with the GNU GPL. We urge you not to use the Ms-PL for this reason.

I figure they would know. 



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