I'm running into a ball of confusion between people on how exactly GFDL limits (or if it does or even can limit) the author's rights.
In our specific case, a copyright holder has provided work to us, licensed under the terms of GNU FDL 1.3. This license specifically allows licencees to redistribute, but limits relicensing of, the work. The copyright holder of the work wants to go on and sell this work to people under different licensing (as part of a book or somethin', so, incompatible with chapter 11).
They're not looking to revoke our rights to the work, we know the license is irrevocable. But we are unsure as to whether the copyright holder has the technical right to go on and sell this work under a totally different license, and who would enforce it if they didn't anyway?
I've tried scouting copyright law for clauses on this, but as one might expect it's rather impenetrable. I feel this should be an obvious question, but at the same time I don't know the law's wording on the alienability of the authors' rights. And I can't find anything reputable online about this.
If a copyright holder distributes their work under the terms of GNU FDL 1.3, can they go on to distribute that work to others under any other license as per their default rights? Can a copyright holder 'waive' their right to redistribute their works under other licenses?