Subject: Re: BSD and MIT license "compliance" with the MS-PL
From: Matthew Flaschen <matthew.flaschen@gatech.edu>
Date: Fri, 17 Apr 2009 12:12:22 -0400

Tzeng, Nigel H. wrote:
> Mmmm...I believe that MPL requires source release only if
> modifications are made. 

No.  "You may distribute Covered Code in Executable form only if the
requirements of Sections 3.1, 3.2, 3.3, 3.4 and 3.5 have been met for
that Covered Code, and if You include a notice stating that the Source
Code version of the Covered Code is available under the terms of this
License, including a description of how and where You have fulfilled the
obligations of Section 3.2."  Section 3.2 requires availability of
source code.

Anyway, I only mentioned MPL as a side point.

> In any case, the FSF calls the MS-PL a copyleft license:
> 
> Microsoft Public License (Ms-PL)
> 
> This is a free software license; it has a copyleft that is not
> strong, but incompatible with the GNU GPL. We urge you not to use the
> Ms-PL for this reason.
> 
> http://www.gnu.org/licenses/license-list.html#SoftwareLicenses
> 
> I figure they would know.

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."

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.

Matt Flaschen