For Approval: Microsoft Permissive License

Chris Travers chris at
Sun Aug 19 20:50:12 UTC 2007

Donovan Hawkins wrote:
> 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.
"This product contains code by .... " on a Help/About screen seems like 
a reasonable requirement by section 7b standards if required in other 
licenses.  "This product is in part based on code by ..." seems 
seimilarly allowed.  Where would the line be drawn?

This doesn't seem to preclude the sort of advertising clauses that 
Internet Explorer must display regarding code from Mosaic.  Or am I 
missing something?  (this is getting off-topic for this thread though).
>> 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.
Agreed.  Sort of like saying "nothing in the GPL prevents you from 
releasing your own 100% original work under the GPL to anyone who flies 
a manned mission to Pluto first" but this seems unlikely to grant any 
reasonable rights....
> 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).
Are the BSD licenses incompatible with the GPL v3 simply because they 
have weaker copleft than GPL v3?
> 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 though.

My argument that optional dependencies might be excluded is that only 
required dependencies are mentioned in the GPL v3 corresponding source 
definition, and optional dependencies do not appear to fall inside the 
four corners of that definition.  Did I miss something in the definition 
of "corresponding source?"

Also "corresponding source" includes a number of loopholes which could 
be used to exclude arbitrary components.  For example, I *could* make a 
Linux device which used closed source libraries as part of an 
authentication system, create a GPL'd application for that device which 
used those same libraries, and exclude them as "system libraries" 
(because they interface with the authentication system which is arguably 
a "Major Component").  If you want to use the application on a different 
Linux device, you have to pay for the required libraries.

> 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 probably depends on what GPL v3 section 7b actually means.  IANAL, 
but I could see how a simple reading of this could allow the 
requirements of the MS-PL.

Does the MS-PL place any specific requirements on the code that the GPL 
does not allow?  If so, what are they exactly?
>> 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".
No actually I don't.  I see it as requiring that MS-PL licensed areas to 
the extent that they are identifiable must be licensed under the terms 
of that license.  This means including the license and (probably, so as 
not to run amok with GPL code copyright owners) identifying the portions 
of the code with reasonable legal notices such as:

/* The block of code including the below function is licensed under the 
MS-PL license.  Please see accompanying ms-pl.txt for details, copyright 
(c) [yyyy] [author_name] */

> 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.

Is the license itself a reasonable legal notice?  If so, then it meets 
7b options and one could force the inclusion of the license.

Best Wishes,
Chris Travers
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