License compatibility of MS-PL and MS-CL (Was: (RE: Groklaw's OSI item

Matthew Flaschen matthew.flaschen at
Fri Aug 24 01:27:34 UTC 2007

Chris Travers wrote:
> Hence I am forced to conclude that the GPL is no different than the MS-PL in
> this regard.

There's a big difference.  The GPL is a copyleft license.  It's position
is that the freedoms granted by the license (and as a consequence the
rights guaranteed by the OSD) should be available to all downstream
users of the code.  One of these is the right to modification, which
requires source code.

The MS-PL calls itself a permissive license, which has traditionally
meant sublicensing is okay, and almost any restrictions can be added.
This allows derivatives to have (among other things) copyleft. Thus,
most permissive licenses are compatible with the GPL, and when they're
not it's usually (always?) not intentional.  While MS-PL is not really
permissive, it does allow proprietary derivatives.

Thus, in my understanding the MS-PL is not really a permissive license,
and yet still doesn't guarantee the OSD rights to all downstream users.
 I am still willing to support approval, if I'm sure the list
understands what it's doing.

Matt Flaschen

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