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

Philippe Verdy verdy_p at
Sat Apr 18 23:30:22 UTC 2009

Matthew Flaschen [mailto:matthew.flaschen at] write:
> Actually, it's quite easy to argue that it doesn't preserve 
> source availability.  A distributes alpha version of Foo 
> under MS-PL.  B makes FooBar derivative, which becomes 
> fanatically popular, and no version of FooBar's source is 
> ever released.  Source availability is denied for almost 
> every user of a Foo derivative.

If B makes that FooBar derivative, and distributes it so widely and still
does not want to release its modified sources (i.e. give the sources to
anyone that wants them, not just to A), it is clearly in violation of FSF
rules (which also says that FooBar MUST come with a written offer allowing
any downstream user to claim for these sources, on a numeric support
customarily used for source distribution, and without more cost than just
the cost of the support media, and shippingand handling, this cost being
nearly zero if the media support for this distribution is an internet
server, or a zipped archive sent by email, but not just to the immediate
users to which B has directly relicenced FooBar).

So it cannot be a free software (FSF), so the MS-PL cannot be claimed to be
free, and not even "viral" (please explain this term, which is not defined
in FSF licences). It is not even open-source for obvious reasons that
there's no sources.

We've seen several cases like this that were very near to finish in courts.
Those companies that created binary derivatives and wanted to maintain
secret on their sources had finally to resign and publish them. They would
have lost a lot due to copyright infringement if they had not finally
accepted the FSF condition.

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