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
Fri Aug 24 00:41:28 UTC 2007

At this point, my view is that the GPL v3 and MS-PL have a similar "no
license but us" restriction.  Matthew has convinced me that the GPL v3
requires that you allow anyone else to reduce terms for redistribution of
any part of the "Corresponding Source" to exactly the level of the GPL v3
with no additional permissions.  Thus the relicense requirement seems to be
the same for both licenses, but is perhaps more limited in the MS-PL case.

Thus it seems to me that if we approve the GPL v3, we have no ability to
hold this specific clause of the MS-PL against it in approval procedings.

Although the GPL v3 doesn't come out and say it, because it allows
additional permissions beyond what the GPL3 grants as a baseline to
components in the corresponding source to be removed in section 7 (and any
restriction of this would be an additional restriction which could itself be
removed also under section 7), this essentially says the same thing.  Unless
your code *can* be licensed or relicensed under exactly this license and
none other by any downstream user, you *may not* include it in the
corresponding source.

Hence I am forced to conclude that the GPL is no different than the MS-PL in
this regard.

On 8/23/07, Michael R. Bernstein <michael at> wrote:
> In this case though, what we have is a license that says (WRT source
> distributions) that no other licenses are allowed. Period. This even
> excludes licenses that have otherwise compatible terms and conditions,
> even those that have *identical* terms and conditions (ie. the same
> license with a name change).

I don't think so.  The license states that derivative works are allowed as
defined by US copyright law.  A few people on this list have provided posts
(that some have declared off-topic) detailing how this applies to software.
The GPL v3 on the other hand requires that you relicense everything they
define (vaguely) as part of the Corresponding Source so that it can, if
downstream licensees so desire, be stripped of any additional permissions.
See section 7 of the GPL v3.

It seems that this would *only* require keeping the license if substantial
portions of the code were copied verbatim and would not affect licensing the
work as a whole under other permissive licenses, or under licenses which
allowed adding appropriate permissions.

This leads me to conclude that if you include MS-PL work in a BSD work
provided that the MS-PL code remains MS-PL.  GPL v3 compatibility is a
bigger mess though because the GPL v3 explitly *requires* licensing the
corresponding source as they define it under a license which allows adding
restrictions to any part and removing additional permissions to any part to
a level exactly equal to the stock GPL v3.  This is not allowed under the
MS-PL (moral opinions on this being irrelevant).

To me, this seems to go beyond incompatibility per-se into
> discrimination.

Sure.  It discriminates against other licenses of similar relicensing
requirements. But if this is a problem for the MS-PL, why is it/is it not a
problem for the GPL v3 which extends this requirement to any required

> OK, this is a valid point, and I guess I haven't explained my pov
> clearly enough.
> In my opinion, even though arbitrary conflicts of terms and conditions
> with other licenses are acceptable (if unfortunate), arbitrarily
> refusing to allow code into or out of the commons where no actual
> conflict of terms and conditions exists is un-free. I suppose it is
> un-necessarily abridging the freedom to modify.

Does the GPLv3 pose this problem?  If you are asking to approve the GPL v3
but not the MS-PL, what difference does it make if the GPL requires you to
be able to remove additional permissions or restrictions in any part of the
corresponding source so that it exactly meets the GPL v3?

To continue your analogy, this is a ghetto where people may enter and
> leave freely as long as they strip themselves of all possessions and
> clothing, with no exceptions.

As opposed to the GPL v3 which simply allows that you allow anyone else to
strip you of all posessions and clothing.

> Nothing is stolen, no taxes are levied,
> everything you leave behind will still be there if and when you return
> or exit, but you can't take anything with you in either direction. More
> importantly, there is no reason for it except control-freakery. This may
> fit some theoretical definition of freedom, but do you truly not see a
> problem here?

This is different from the GPL v3, how?

> Nothing in open source has ever, to date, barred the creation of badly
> > conceived commonses that will likely eventually fall flat on their
> > faces.
> >   The proper remedy, IMVAO, is to watch and _find out_ whether
> > they fall flat on their faces.  And meanwhile, you're free to tell
> > people "That's a sucky licence."  News flash:  The OSI approved list
> > includes many sucky licences, already.
> True, but on this list we've occasionally discouraged sucky licenses
> from completing the approval process. And as I said, I think that these
> licenses are not just sucky, but also mildly un-free, even though the
> OSD does not currently exclude this particular flavor of un-freedom.

What makes the MS-PL sucky in this way that is not the case for the GPL v3?

> > Or perhaps this: A license may not discriminate against other licenses
> > > or groups of licenses.
> >
> > Nice can of worms you have there.  Make sure you have plenty of room.
> > ;->
> I don't really think this is a can of worms. I've repeatedly stated that
> incompatibilities aren't objectionable in and of themselves. I just
> think there is a difference between a license that is incompatible with
> other licenses (for example reciprocal licenses) due to a conflict of
> terms and conditions and one that baldly says "the GPL is excluded" or
> "reciprocal licenses are excluded".
> In this case, of course, what I object to is the MS-PL excluding *all*
> other licenses from source distributions, which though it is certainly
> even-handed in it's contempt, I still find discriminatory.

How does this differ from the GPL v3?

Do you feel that we should approve one and not the other?  What makes the
relicensing requirements of the GPL v3 ok but those of the MS-PL not?

At the moment, I am convinced that both are sucky licenses ;-)  But none of
the problems you raise seem to apply only to the MS-PL.  Every one of them
also applies to a license which nobody objects to approving.

So I guess I am assuming both will be approved.

Best Wishes,
Chris Travers
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