For Approval: Microsoft Permissive License

Chuck Swiger chuck at
Fri Aug 10 23:54:03 UTC 2007

On Aug 10, 2007, at 4:35 PM, Donovan Hawkins wrote:
> On Fri, 10 Aug 2007, Jon Rosenberg (PBM) wrote:
>> *         Can MS-PL code be redistributed under a different license?:
>> No.  The license states that "If you distribute any portion of the  
>> software in source code form, you may do so only under this  
>> license..." This restriction is similar to the restriction in the  
>> Mozilla Public License that states "You may not offer or impose  
>> any terms on any Source Code version that alters or restricts the  
>> applicable version of this License or the recipients' rights  
>> hereunder."
> (As an aside, I just noticed that both Mozilla Public License and  
> Microsoft Permissive License are "MPL"...I'll use MozPL and MicroPL  
> below.)

MPL is well-understood to be the abbreviation for Mozilla's license.   
I've seen the newly proposed licenses called either MSPL or MS-PL;  
this seems to work well enough to prevent confusion.

> The MozPL also has an explicit statement in section 13 that permits  
> the initial release under MozPL combined with another license. Both  
> the MicroPL and MicroCL lack a clause like that. While I doubt the  
> license agreement could prevent the original author from releasing  
> under as many licenses as he chooses, it seems like a similar  
> clause would clear up misunderstandings in cases where both  
> releases come packaged together with a single license document (a  
> very likely scenario).

Clause 2(a) and 3(d) suggest that you can prepare and distribute  
derivative works, so long as the source code which was originally  
licensed under the MSPL remains under the MSPL.  There are no  
explicit restrictions against combining such code with source code  
under other licenses, unless the other license forbids the  
combination.  In other words, the MSPL + BSD/MIT/Zlib/Apache2 code is  
fine, but MSPL+GPL or similar is not.

> Also, isn't the name "Permissive" rather misleading?  While you are  
> free to release binaries however you choose, the license is viral  
> and the source code cannot be used by the vast majority (ie, any)  
> of the existing open-source projects. I would hardly call that  
> permissive...the word carries a lot more meaning than "non-copyleft".

A "viral" license is one which requires that a combination of code  
under that license and other software, to only be distributed under  
the terms of the viral license.  The MSPL isn't viral in that sense;  
instead, it is reasonably close to the "new" or "modified" BSDL,  
which is considered a canonical example of a permissive license.


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