Hi Ludo’, all,

Ludovic Courtès <ludo@gnu.org> writes:

> Hello,
>
[...]
> I would propose GFDLv1.3+ without invariant sections, since that can
> then be relicensed to CC-BY-SA should anyone need it.
>
> Thoughts?
>
> Ludo’.

I'm not a lawyer and this is not legal advice, but reading the text for
GFDLv1.3 <https://www.gnu.org/licenses/fdl-1.3.html>, specifically
"11. RELICENSING", it seems to me that the explicit permission to
relicense GFDLv1.3-covered work to CC BY-SA 3.0 was only valid until
August 1, 2009.  Thus, I would suggest explicitly asking the FSF or
seeking legal advice about that, to know whether that section still
applies today.

Another good candidate is CC BY-SA 4.0, which was declared one-way
compatible with GPLv3
<https://www.fsf.org/blogs/licensing/creative-commons-by-sa-4-0-declared-one-way-compatible-with-gnu-gpl-version-3>;
but it does have its own gotchas
<https://wiki.creativecommons.org/wiki/ShareAlike_compatibility:_GPLv3#Option_to_comply_with_later_versions>.
I have also seen folks license material on their site under GPLv3+.
I currently do that for the material on my personal site.

That's my 2¢; hope it helps.