GPLv3's secretive Additional Terms

[John Cowan]

opensource.*.nwo at neverbox.com scripsit:

> GPLv3's possibly most secretive addition is section 7. Additional Terms. 
> The GNU site and the online world in general pretend like it doesn't 
> exist. I'm especially baffed by the statement "when you convey a copy of 
> a covered work, you may at your option remove any additional permissions 
> from that copy."

The key to understanding 7 is to distinguish between additional
permissions and additional restrictions.  The first are things that you
want to allow that the GPL would not by itself allow; the second are
things that you want to forbid that the GPL would not by itself forbid.

You can add any additional permissions that you want; for example, you
can allow the LGPLv3 permissions, or allow people to use your library
unrestrictedly in proprietary code, or whatever you like.  Anyone who
gets a copy of your code, though, can remove the additional permissions
in their own copies, leaving the unmodified GPL.

Additional restrictions are of two types, the five special cases a-e
that are called out in 7, and everything else.  You can add any or all
of the five special cases to your code, and nobody can remove them.
This is typically done because parts of your code are under non-GPL
licenses such as the Apache 2.0 that impose these restrictions.  If you
add any other restriction, though, the recipient can ignore it.

> Can you deal with this section in your FAQ to help stop such 
> disinformation? My main desire is keeping my name attributed (section 7's 
> item b) in the footer of my web apps, unless agreed otherwise.

Well, nobody can remove a 7b restriction, so you can say "GPLv3 plus
name in the footer", and that's the license for all downstream copies
and versions.

-- 
"Well, I'm back."  --Sam        John Cowan <cowan at ccil.org>