License compatibility of MS-PL and MS-CL (Was: (RE: Groklaw's OSI item (was: When will CPAL actually be _used_?))

Donovan Hawkins hawkins at
Sat Aug 25 20:33:53 UTC 2007

On Sat, 25 Aug 2007, Zac Bowling wrote:

> The text about "any portion of the software" is unclear. Does it mean
> any portion of the combined work or any portion of the original work?
> Saying "any portion of the software" led us to believe that it was the
> combined work.

In the very first line you can see that it is a shortening of "the 
accompanying software":

"This license governs use of the accompanying software. If you use the 
software, you accept this license. If you do not accept the license, do 
not use the software."

I don't see anything that would suggest that the meaning changes.

> I blogged the issues of using Ms-PL on my blog about a week ago based
> purely on our combined interpretation.

Except you don't seem to say anything in your blog that suggests you 
disagree with the interpretation that MS-PL is incompatible with other 
licenses at the source code level. You even make a request to see this 
changed to at least offer MS-CL compatibility, so you apparently agree 
that it is not compatible currently. See below for why that won't happen.

> Would it be possible to clarify this in the text of the licence?

It really doesn't seem all that unclear in the text of the MS-PL. I wonder 
if people are just being too optimistic in their readings trying to find 
compatibility where none was intended.

MS-PL is to closed source what GPL is to open source. It ensures that 
downstream closed-source developers will not be hindered by copyleft, 
which therefore excludes compatibility with the MS-CL. This was the stated 
intention of the MS-PL:

"A design goal of the MS-PL is to allow developers to choose to ensure 
that the specific rights in Section (2) continue to be available to 
downstream developers and users through generations of adoption and 

Compare that to this quote from the GPL v3 preamble:

"...the GNU General Public License is intended to guarantee your freedom 
to share and change all versions of a program--to make sure it remains 
free software for all its users."

Allowing compatibility with copyleft licenses would take away section 2 
rights from downstream closed-source developers. What you're really asking 
for is the BSDL (although the BSDL is silent regarding patents and could 
probably use a bit of updating in that regard).

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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