Folks: Mike Linksvayer asked me if I was aware of Ted Ts'o's Temporary Proprietary License. I was not consciously aware of it when I developed the Transitive Grace Period Public Licence. I exchanged email with Ted about it later. One particular detail of my TGPPL that I value and that I'm not sure the TPL provides is that if you take advantage of the permission to keep a derived work temporarily proprietary, then this obligates you to offer the same permission to people who make worked derived from your derived work. Make sense? So when I publish source code under the TGPPL, I'm not offering people the option of making a derived work, keeping it proprietary for a limited time, and then releasing it under a strict copyleft which disallows others from making time-limited proprietary derived works of it. On the other hand, I *am* offering people the option of making a derived work, making it Free/Open immediately, and disallowing others from making a proprietary derived work from it, even for a limited time. The latter option is currently the case for Tahoe-LAFS and the other software that I release in this way because I offer the recipient the choice of GPL or TGPPL. So if you want to make a derived work of Tahoe-LAFS without allowing anyone "downstream" of you to make a proprietary derivation of your work, even for a limited time, then you can do so by releasing your derived work solely under GPL. I'm interested in developing a "TGPPLv2" which is expressed as an "Additional Permission" to GPL. That would have exactly the same consequences as the current TGPPLv1, sketched above, but it would probably be better in a lot of ways to have it expressed as an "Additional Permission" to GPLv3+. Mike posted some criticism of the very idea of TGPPL which I'd like to (briefly‽) address. Mike wrote: I agree that reliable evidence about this is difficult to come by. Nonetheless, I believe I should act based on my current understanding rather than hesitate while looking for better data. I personally have pretty high confidence that copyright maximalism, including "Limited Time → ∞", will yield a worse social outcome than some alternatives. More controversially in some circles (presumably including this one), but less controversially among mainstream economists, I have pretty high confidence that pure copyleft, in which "Limited Time = 0", will yield a worse social outcome than some alternatives. My reason for believing that latter assertion is that I think the production and usage of Free/Open software on earth has grown only modestly over the last couple of decades, while production and usage of all software has exploded immeasurably. Software has changed everything for billions of humans, it appears likely to do so even more rapidly in the coming decades, and Free/Open software is less and less important to that. Free/Open software is a tiny and rapidly shrinking sliver of all software, as measured by human values -- how much time people spend with it, how much of their money, their memories, their rights and freedoms they entrust to it, etc. A typical situation is that the lower-layer and more commoditized parts of the software stack are more likely to be Free/Open, e.g. operating systems and web browsers, and the higher-layer and newer parts are more likely to be proprietary and to otherwise deny freedom to their users, e.g. Facebook and more or less the entirety of the Web. It is those newer and higher-layer services that are most valuable to users and most dangerous to their freedoms. For the vast majority users it would make little difference to them if you switched their Windows for Linux or their MSIE for Firefox, but it would be unthinkable for them to leave Facebook, or migrate off of Oracle, or stop subscribing to the software vendors and web sites that they rely on, etc. So, I personally believe Free/Open software is a social good that is massively, drastically under-produced, just as simple economic theory would predict. I think -- or rather I hope -- that a better social outcome is possible somewhere in the middle, between the two extremes of 0 and ∞. TGPPL is my stab at it. We can't do much worse than we are already doing. ☹ I recognize that this may be surprising or unpleasant to this audience. I mean no offense. You are the big fish in a pond. I'm asserting that beyond this pond, the world of bigger ponds is growing at an incredible rate. I very much value and respect your contributions, including those of Red Hat, which can be measured in real money. I don't think it is a valid comparison. Aladdin never offered to anyone the option that they could make a proprietary derived work for a limited time. So it provides no evidence on whether anyone would have been interested in that option. Now Tahoe-LAFS *has* offered people that option, and so far, to my knowledge, nobody has taken us up on it. This probably just shows how there is little commercial interest in Tahoe-LAFS, but it could also be taken as evidence that the TGPPL is not itself a big draw for investment. By the way, commercial interest in Tahoe-LAFS is growing -- there are now three companies offering commercial services based on it including my own startup, and I'm aware of a few other expressions of commercial interest. Thank you for your attention. Please accept my bold, normative statements in the spirit of constructive criticism that I intend. Regards, Zooko Wilcox-O'Hearn Founder, CEO, and Customer Support Rep -- Least Authority Enterprises https://leastauthority.com