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

[zooko]

Dear licence-review:

Thank you for your comments.  Bruce Perens, Simon Phipps, and Matthew  
Flaschen all asked about "an exception form".

For a bit of history, earlier versions of my software were  
distributed under just such an exception form, but as applied to the  
GPLv2 instead of to OSLv3.  I spoke with Eben Moglen, who told me  
that this couldn't work.  Specifically, the GPL declares itself to be  
incompatible with any addition or exception that imposes an  
additional requirement on the user.  The exception that I had written  
imposed an additional requirement -- namely the requirement of  
granting that same exception to your users (transitively).

(Prof. Moglen also colorfully offered that he disapproved of the idea  
and of my boldness in venturing to craft new licence terms without  
being admitted to the bar.  He further mentioned that, if RMS so bade  
him, he would sue me for using the GPL in this way.  I was curious  
what legal principle, if any, backed that threat, but finding out is  
lower on my list of things to do than quite a few other projects.)

Therefore I copied the OSLv3 and amended it to include the grace  
period clause in the text itself, resulting in the TGPPLv1.  The  
TGPPLv1 makes it clear that the licence is conditioned on the  
transitive grant of the TGPPL to derived works.  It is clear that the  
TGPPLv1 does not grant the right to distribute a proprietary derived  
work for 12 months and then to open source the derived work under  
different licence terms than those of the TGPPL.  (During the process  
of crafting the TGPPLv1 I sought the advice of Larry Rosen, who  
offered a few words of advice, and a few more words of discouragement.)

As I understand it, an exception to the OSLv3 would not have that  
same consequence.  Even if someone argues that such a transitive  
requirement could be crafted as an exception, it would be harmfully  
ambiguous whether software was licensed under OSLv3 or under OSLv3- 
with-1c-waived-for-12-months-and-transitively-requiring-that-waiver.

I hope that this answers why I use TGPPL instead of an exception  
clause to another licence.

Regards,

Zooko
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