I'm pleased to see that documentation writers are trying to figure
out a way to clean up some issues with the GNU FDL. It seems,
though, that some of the commenters are getting sidetracked by side
issues.
Side issue #1: even a GFDL with exceptions is still going to be GPL
incompatible. True, but that's also the case for several other
licenses that are considered DFSG-free, so the point isn't relevant
for this discussion. We can recommend dual licensing, but don't need
to require it.
Side issue #2: people can add invariant sections later. If so, then
those derived works would be non-DFSG-free, but the original work
would still be free. The LGPL has similar issues.
Side issue #3: claims that we should tell people to use the GPL for
documentation. That's a bad idea, as if I sell my GPL-covered printed
book to a friend, and that book was produced from, say, DocBook SGML, I
have to either give the friend the SGML source code, or else give him a
written offer, good for three years, to give him the source code later.
There is good reason for debian-legal to be thinking about licensing
specifically designed for documentation, and the GFDL does have some good
ideas, even if it is seriously flawed.
Side issue #4: claims that a license with exceptions would be a
non-copyleft. No; derivative works still have to be licensed on
the same terms.
The proposal from Nathanael in
http://lists.debian.org/debian-legal/2004/09/msg00451.html
seems like a good starting point. That is, allow "DRM restriction"
as long as distributors also provide unencumbered copies, and remove
the requirements of section 3.
I would suggest producing some short, standard exceptions language,
starting from what Nathanael wrote.
I would also suggest adding text like the following:
"These exceptions are granted for derivative works only if those works
contain no Invariant Sections, no Front-Cover Texts, and no Back-Cover
Texts."
That would provide a disincentive for people contemplating adding those
sections, as they are then bound by extra requirements for printing in
bulk that they otherwise would be freed from.
Dual licensing with the GPL might be a good idea as well, but it is
orthogonal to DFSG-freeness.
