GFDL / CC by-sa compatibility

Anthony DiPierro wrote:
>I sure hope this is made optional.  I don't want my free works 
>altered and made non-free. 

Both the GFDL and the CC by-sa are free content licenses. But the GFDL with 
invariant sections is less free than the GFDL without them (and the CC by-sa 
is freer than even the invariant section-free GFDL text). No Wikimedia 
project allows invariant sections for this reason. 

>They can't possibly be compatible.  A derivitive of something 
>released under by-sa has to be released under by-sa.  That means 
>you can't enforce invariant texts or cover texts, you can't require 
>that "secondary sections" be about a particular subject matter, 
>you can't force copies to be "transparent," you can't restrict 
>titles, you can't limit the number of copies which can be 
>distributed in a particular manner, and you can't require a 
>"history" section    

I think RMS was more concerned with compatibility in spirit, not the letter of 
the law. Jimbo was in fact baffled that RMS would suggest that the current CC 
by-sa and the current GFDL are compatible in any real world sense. You point 
out some reasons why this obviously is not so. 

However the "or later versions" clause of the GFDL gives the GNU people a way 
to add explicit compatibility for transferring invariant section-free GFDL 
text to the CC by-sa. When that would happen all the GFDL-specific 
requirements would be trimmed and the end user could use the text under just 
the by-sa. The same would be true in the other direction if the CC people did 
the same thing but in reverse. The common requirements between the two 
licenses would be a de-facto bare bones free content license. We could codify 
that into a Lessor GFDL. 

One problem with the current CC by-sa is that there is no "or later version" 
clause in by-sa 1.0. So I don't know how a project like Wikitravel could even 
upgrade to the new version of the by-sa without having to get the permission 
of every one of their contributors (past, present and future). 

Evan, you listening? I remember pointing this out soon after Wikitravel 
started and you said you were going to contact the CC people about that.

http://www.wikitravel.org/article/Wikitravel:Copyleft

-- Daniel Mayer (aka mav)