Re: [dev] [license] gpl issues

From: Markus Wichmann <nullplan_AT_gmx.net>
Date: Sun, 18 Jun 2023 16:15:35 +0200

Am Sun, Jun 18, 2023 at 11:44:18AM +0200 schrieb Hiltjo Posthuma:
> Hi,
>
> I think you can relicense only your own changes to GPL, so you'd have to keep
> both the MIT and GPL license with the original copyright information.
>
> And probably explain very clearly to which new parts the GPL license applies.
>

This is false. When you create a program, call it foo, and release it
under the MIT license, then you give permission to anyone to re-release
it with or without changes. Great.

Now I come along, create a program bar, and base it upon foo. bar is a
derivative work of foo, and so I as creator of bar need permission from
you as creator of foo to create it. Luckily I have your permission. It
is in the license (license and permission mean substantially the same
thing).

So I can release all of bar under the GPL. All I have to do is write
into the documentation:

bar, Copyright Markus Wichmann, released under the terms of the GPL, see
file COPYING. Based on foo, Copyright Hiltjo Posthuma, released under
the terms of the MIT license, see file COPYING.foo.

That way, I have fulfilled the terms of your license and am therefore
allowed to create a derivative work (which I would class under a mix of
"use", "copy", "modify", and "merge"). And for my own work, I can use
whatever license I wish, and I choose the GPL. I could also choose a
commercial license. So long as I fulfill the terms of your license, that
is all OK for me to do, since that is what you have given me permission
to do.

The other way around would not work, since if I create a work and
license it under the GPL, then I do not give you permission to rerelease
the work without restriction. I only allow you to do so under the same
license terms.

Summary: Words have meaning.

Ciao,
Markus
Received on Sun Jun 18 2023 - 16:15:35 CEST