For Approval: Microsoft Permissive License

Donovan Hawkins hawkins at
Sun Aug 19 20:07:00 UTC 2007

On Sun, 19 Aug 2007, Chris Travers wrote:

> Hmmm.... First GPL v3 section 7b may provide compatibility with BSD-like 
> licenses with advertising clauses depending on how obtrusive they are (the 
> FSF's comments to this effect seems to indicate that they are concerned about 
> proliferation of such advertising notices, not the original notices 
> themselves). Thus compatibility with these licenses may be case-by-case. 
> IANAL and YMMV....

7b allows "requiring preservation of specified reasonable legal notices or 
author attributions in that material or in the Appropriate Legal Notices 
displayed by works containing it."

The phrase "that material" refers to an earlier mention of the "material 
you add to a covered work". So 7b allows attributions and notices in the 
material you add to a covered work and in the notices displayed by the 
covered work.

Advertising that someone else creates for their derived work is not the 
material you added to the covered work, and it is not a notice displayed 
by the covered work. IANAL, but that doesn't seem to cover the old BSDL 
advertising clause.

> I have concluded that there are major license 
> compatibility problems if a GPL v3 application *requires* components under 
> these licenses.

GPL v3 doesn't appear to prevent anyone from releasing their code under 
GPL v3 combined with code under an incompatible license. You just can't do 
that with someone else's GPL v3 code, because that is not a right that GPL 
v3 grants you.

Of course, it would rather pointless for you to do it with your own code 
unless you never intend to have anyone create derivative works. They would 
be forced to remove either your code or the code under the other license 
in order to proceed.

I'd say you are correct in pointing out that GPL v3 creates "major license 
compatibility problems", since it is intentionally incompatible with any 
license that has weaker copyleft than GPL v3 (which includes many if not 
most open source licenses).

> Like many other aspects of the GPL v3, it is hard to say 
> whether optional dependencies would be a problem, and it is harder to 
> evaluate the MS-PL which may be compatible.

I believe some have claimed that linking to GPL code is not as forbidden 
as the FSF would like it to be, so optional dependencies can perhaps be 
implemented in that way. I don't see why having something optional via, 
say, conditional compilation in the code would be allowed by the GPL 

I also don't see how GPL v3 could be compatible with MS-PL, in the sense 
of combining code from GPL v3 with code from MS-PL in a single program.

> It seems clear to me that any component falling under the Corresponding 
> Source definition must be able to be distributed under terms of which the GPL 
> v3 must be either identical or a proper subset. Because the MS-CL provides 
> per-file restrictions, I don't see how this could be met.
> The MS-PL is harder for me to evaluate. A lot of it depends on what 7b 
> additional terms allow under the GPL v3. The MS-PL could be read as requiring 
> the distribution of the license as a legal notice (seems reasonable to me) 
> and possibly noting which sections of code are MS-PL-licensed. Again, this 
> seems to be in line with the GPL v3 7b options by my reading.

I imagine that maintaining a copy of the MS-PL as a legal notice could be 
done under section 7b of GPL v3. Now the question comes down to your 
reading of the MS-PL where it says:

"If you distribute any portion of the software in source code form, you 
may do so only under this license by including a complete copy of this 
license with your distribution."

Your interpretation of the word "by" seems to be equivalent to "which is 
accomplished by". I'll let others address that, but I don't think I agree 
with your reading. If you take the "by" as indicating that said licensing 
is incomplete without including a copy, then there is no way to meet the 
requirements of section 5c of GPL v3.

> Again, I don't think this is a problem, and as a developer probably wouldn't 
> worry about it. But I could see it being a question when people look at 
> trying to split hairs to their own substantial benefit.

Well, I wouldn't worry about it either...I would just assume I can't mix 
GPL v3 code with MS-PL code in any useful way.

Donovan Hawkins, PhD                 "The study of physics will always be
Software Engineer                     safer than biology, for while the
hawkins at                   hazards of physics drop off as 1/r^2,                biological ones grow exponentially."

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