License compatibility of MS-PL and MS-CL (Was: (RE: Groklaw's OSI item (was: When will CPAL actually be _used_?))

Chris Travers chris.travers at
Tue Aug 28 17:53:53 UTC 2007

IANAL, of course.

On 8/28/07, Matthew Flaschen <matthew.flaschen at> wrote:
> Rick Moen wrote:
> I agree on both counts.  However, it seems clear Jim agrees MS-PL code
> can not really be part of a GPL project (certainly not with the GPL
> project distributed intact).  This means MS-PL is not GPL-compatible
> (and perhaps not compatible with other copyleft licenses), and thus I
> would welcome a change in the title before approval.

Let me pose a possible counterargument to MS-PL/GPL3 compatibility.

The argument over BSDL/GPLv3 compatibility seems to be that "relicensing"
does not have any effect until the code is changed to encumber it with
copyrights of a new author.  However, suppose we extend the BSDL slightly to
conform to the language of the GPL3 but place an equivalent restriction as
the MS-PL:

* Any portion of this code which has not been substantively altered must
bear a notice stating that it is still original, is authored by <author>,
and has been publically licensed by the author under the terms of this
modified BSD license.  One may use additional comments to indicate ends of
such sections.

Would such a BSDL now be incompatible with the GPL3?  Would this be allowed
under the 7b legal/attribution notices?

Now, what affect does this have in practice?  In my view, it identifies
which sections of the code can safely be extracted without infringing on the
GPL work's copyrights (since they don't extend to the excerpt).  Such
fragments would effectively be encumbered *only* by the BSDL + additional

Now, how does this *functionally* differ from the MS-PL?  Is it possible to
use the same approach to merge GPL3 and MS-PL code together?  Therefore is
the MS-PL really any less compatible with the GPL3 than the BSDL?

Best Wishes,
Chris Travers
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