MS-PL/GPL compatibility, was Re: For Approval: Microsoft Permissive License

[Chris Travers]

On 8/22/07, Tobia Conforto <tobia.conforto at linux.it> wrote:
>
>
>
> If I take a MS-PL file and a GPL file, combine them into a derived work
> and release it as GPL, the license of the whole work will say, among
> other things: "You may copy and distribute the [whole work] ... provided
> that you ... accompany it with the complete ... source code."
> Thus you are placing restrictions on the MS-PL part that were not there
> in the original license.  You have modified its license.  Verboten!


Not necessarily.  We can all agree that the GPL v2 is incompatible with the
patent termination clause of the MS-PL so let us look at the GPL v3:

Section 5 lists the conditions of distributing the work.  5c is of paticular
interest:
"You must license the entire work, as a whole, under this License to anyone
who comes into possession of a copy. This License will therefore apply,
along with any applicable section 7 additional terms, to the whole of the
work, and all its parts, regardless of how they are packaged. This License
gives no permission to license the work in any other way, but it does not
invalidate such permission if you have separately received it."

Note the "it does not invalidate such permission if you have separately
received it."  In short, the license as a whole must not be restricted by
licenses of component parts, but if a component part is under a more
permissive license, the GPL work as a whole does not restrict those
permissions nor require you to do so for works under licenses that offer a
superset of permissions.

In short the GPL v3 does not require that you extend the restrictions to
original components of your work, nor does it require that you extend the
restrictions to components which are licensed in ways which grant a superset
of GPL v3 permissions.

The essence of 5c is really this: "You must license the entire work, as a
whole, under this License.... This License gives no permission to license
the work in any other way, but it does not invalidate such permission if you
have separately received it."   I see the middle section: "This License will
therefore apply, along with any applicable section 7 additional terms, to
the whole of the work, and all its parts, regardless of how they are
packaged." to simply ensure that no additional restrictions can be added
beyond those of the GPL.

This is further stated in section 7:
'All other non-permissive additional terms are considered "further
restrictions" within the meaning of section 10. If the Program as you
received it, or any part of it, contains a notice stating that it is
governed by this License along with a term that is a further restriction,
you may remove that term.'

If one is *required* to restrict, why are additional permissions
specifically excluded from the terms that can be removed?

Best WIshes,
Chris Travers
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