GFDL / CC by-sa compatibility

Anthony DiPierro wrote:
>The GFDL with invariant sections is not free.  In order to make 
>by-sa compatible with the GFDL, you would have to allow 
>invariant sections. Thus, my free works could be altered 
>and made non-free. 

That is a matter of opinion. Many people in the Debian project say that but 
RMS and the FSF disagree. I happen to agree with the FSF on this.  But yes, 
anything under the updated CC by-sa could be transfered to the GFDL and 
somebody could add invariant sections. This is already true for /all/ 
Wikimedia content but I'm not aware of anybody doing this with our work. So 
it is just hypothetical. 

Also, since the CC by-sa does not provide for invariant sections I'm sure a 
rewritten GFDL would state that GFDL content with invariant sections could 
not be licensed under the CC by-sa (otherwise anybody could easily remove the 
sections). IMO, RMS seems very stubborn on the invariant sections issue and 
does not seem willing to get rid of them in future versions of the GFDL (I 
wish they were; the thought of invariant sections being used to make free 
content less free bugs the hell out of me). 

>Yes, the CC people could do the same thing in reverse, but 
>once again this would be equivalent to someone dual 
>licensing under both licenses.  I don't see the point.

The point would be that text licensed in one could be mixed and matched under 
the other. Dual licensing would be different: 
1) It would require the compilation licensor (us) to adhere to the entire 
terms of both the GFDL and the CC by-sa. 
2) It would require the licensee (any user of our content) to choose either 
GFDL or the CC by-sa. They could not choose both. Thus any modifications they 
make to the text cannot be re-incorporated back into Wikipedia. 

But having both the CC by-sa and the GFDL explicitly compatible would greatly 
simplify things and make it freer:
1) It would require the compilation licensor (us) to adhere to the terms of 
just one license. 
2) It would give the licensee the freedom to choose either the GFDL or the CC 
by-sa depending on their needs (admittedly not much different than with dual 
licensing). However, any modifications they make to the text can be 
re-incorporated back into Wikipedia (or the CC by-sa Wikitravel).

-- Daniel Mayer (aka mav)