Subject: Re: BSD and MIT license "compliance" with the MS-PL
From: Matthew Flaschen <>
Date: Fri, 17 Apr 2009 13:47:18 -0400

Tzeng, Nigel H. wrote:
> 3.2 requires source availability of modifications to source code.  1.9 
> Defines what modifications are.

Yes, but 3.6 says 3.2 applies for /any/ executable-only distribution
(meaning there has to be source offer) of Covered Code.  The Mozilla FAQ
corroborates this.  It doesn't say it only applies for executables made
from modified code.  See ,
specifically "I want to distribute Firefox (or other MPL-covered code)
that I have compiled myself but not changed. What do I have to do?"

>> Anyway, I only mentioned MPL as a side point.
> It's not a side point if you assert that all copyleft licenses require
> source distribution with all binary distributions and one does not.  

If MPL didn't require source distribution, then MPL wouldn't be
copyleft.  That doesn't change the definition of a word.  But you have a
very heavy burden in trying to prove Mozilla interprets their own
license wrong on this fundamental point.

>> In this instance, I disagree with license list.  The FSF defines
>> copyleft as, "Copyleft is a general method for making a program or other
>> work free, and requiring all modified and extended versions of the
>> program to be free as well."
> That is the definition for strong copyleft yes.

No.  The difference between strong copyleft is whether new files are
included in the copyleft.  Trivial example:

Original program made from A.c and B.c, both under weak copyleft license.

Derivative program made from A.c, B.c, and X.c.  X.c does not need to be
under the copyleft license.

>> Clearly, if I release a Ms-PL program there is no guarantee all future
>> derivatives will remain free.  One or more branches of the source code
>> could be closed off forever.
> This is true of all permissive licenses.

True.  Ms-PL is permissive and not copyleft

  Perhaps the MS-PL license was not
> accidently named and appropriately categorized as a permissive weak-copyleft 
> open source license.

Where is it categorized as copyleft (besides the FSF list)?

> It is probably not in our interests to call any copyleft license "viral"
> even if we don't particularly care for it.  There are already too many
> nuances in open source licenses to voluntarily reopen that can of worms.

It's not copyleft, so if you don't like viral invent a new word.  To me,
though, it's mostly reclaimed.

Matt Flaschen