For Approval: Transitive Grace Period Public Licence, v1.0

zooko zooko at
Tue Feb 17 20:20:06 UTC 2009

On Feb 5, 2009, at 4:19 AM, Russ Nelson wrote:

> The board is not comfortable with the discussion of the transitive  
> quality of this license, and would like more discussion by license- 
> review members.  Thank you for the discussion so far.

Okay, are there any questions for me?

The web page about this process says that one of its purposes is to  
"ensure a thorough, transparent, and timely review (e.g., within 60  

 From my perspective, this process has so far been thorough and  
transparent, but not timely.  I initially posted the Request For  
Approval on December 14, 2008, so 60 days from then was last week.   
(I had been hoping to get the OSI's stamp of OSD-conformance for  
Valentine's Day, but no such luck.)

There was some confusion initially because I failed to make clear how  
the TGPPL's requirement of transitivity made it different from  
licensing practices that have used by e.g. L. Peter Deutsch of  
Ghostscript, John Carmack of id Software, and Peter Braam of Cluster  
Filesystems, Inc..  I'm sorry for that.

The discussion to date as I understand it shows:

1.  There is no doubt that the TGPPL is an open source licence,  
conformant with the Open Source Definition.

2.  Originally some contributors to the list thought that the TGPPL  
was unnecessary because the same effect would be had by using a  
transitive open source licence such as GPL or OSL, combined with a  
time-limited waiver of certain requirements.  Subsequently it was  
agreed that this does not have the same effect, because such a  
practice does not necessarily result in a "grace period" right that  
is transitively available to all recipients of derived works.

3.  It might be the case that some contributors think that the  
"proliferation" problems caused by the existence of another open  
source licence exceeds the beneficial effects offered by the TGPPL.   
(Bruce Perens recently wrote a nice essay on this topic entitled "How  
Many Open Source Licenses Do You Need?".)

I understand the motivation behind such an opinion, and I respect the  
knowledge and experience of the contributors to this list.  That  
opinion may turn out to be correct, but I am finding out by trying  
it: explaining the potential value of the TGPPL to others,  
distributing software under the TGPPL myself, and trying to observe  
what value is gained.  In any case, the topic under discussion is not  
whether the TGPPL should exist, but whether it is OSD-conformant.  I  
am not asking OSI to recommend the TGPPL to others nor to classify it  
as a popular and actively used licence, only to agree, in a public  
and permanent form which I can reference, that the TGPPL is indeed  

By the way, last week we released version 1.3 of the tahoe-lafs  
secure decentralized cloud storage system.  I'm very pleased with  
this project -- it is software of excellent quality and offers  
interesting properties not offered elsewhere.  We have a growing  
number of contributors from outside, all of whom have  
readily agreed to license their contributions under the same terms as  
tahoe-lafs itself.  For this release, I edited the explanatory text  
about the licensing, in part because of the discussion from this  
thread.  It now says:

All of the source code is available under a choice of two Free  
Software, Open Source licences.
You may use this package under the GNU General Public License,  
version 2 or, at your option, any later version. See the file  
COPYING.GPL for the terms of the GNU General Public License, version 2.
You may use this package under the Transitive Grace Period Public  
Licence, version 1.0. The Transitive Grace Period Public Licence has  
requirements similar to the GPL except that it allows you to wait for  
up to twelve months after you redistribute a derived work before  
releasing the source code of your derived work. See the file  
COPYING.TGPPL.html for the terms of the Transitive Grace Period  
Public Licence, version 1.0.
(You may choose to use this package under the terms of either  
licence, at your option.)

Please include the Transitive Grace Period Public Licence, v1.0, on  
the list you maintain of Open Source Definition-conformant licences.

Thank you for your time.


Zooko Wilcox-O'Hearn
Tahoe, the Least-Authority Filesystem --
store your data: $10/month --

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