Partial OpenSource products/licenses?

Mitchell Baker mitchell at
Wed Oct 2 17:53:52 UTC 2002

I believe the difference is that the MPL does not require two versions 
of the same code, one open and one closed.  

Our system is to allow one version of the open tree, to which everyone 
would contribute.  Copernicus would also keep a second tree, containing 
the closed source material.
Copernicus would participate with everyone in the open source project. 
 When Copernicus builds its commercial product, it would pull form the 
open source project, then add in closed source additions to build its 
commercial product.  Returning to the Netscape example, this is what 
Netscape does.  Netscape engineers participate in the source 
tree, and get the critical benefits of the open source project.   
Netscape pulls from that open source tree, then pulls from a separate 
closed source commercial tree to complete its product.  This means 
anyone can pull the same thing from mozilla as Netscape does.  (Any many 
do, forming the variety of Mozilla distributions.)   But no one else can 
pull from Netscape's commercial tree, because that remains proprietary 
to Netscape.

I use Netscape as an example because it is so well known, but numerous 
other companies do the same thing as well.


Lewis Collard wrote:

>John Cowan:
>>That way lies great pain and suffering for everyone.
>>Instead, I recommend you use the Mozilla Public License, and have two versions
>>of your product.  "ProductX Open" is fully open source under the MPL, which
>>basically allows people to create closed-source derivatives as long as they
>>reveal actual patches to the source (as opposed to additions).  "ProductX
>>Gold" is a derivative of ProductX Open, but is closed-source.  By using
>>the Netscape modification to the MPL (see the NPL), you can have patches
>>submitted to ProductX Open made reusable in ProductX Gold as well.
>Couldn't you use the GPL too for this purpose? If you are the copyright
>holder for the entire code is there anything stopping you from releasing
>modified versions under different licenses?
>	-- Lewis

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