Tomasz Wegrzanowski wrote: Similarly, the Open Document License has free options A and B. Enabling them renders the licence non-free; the fact that they may be enabled later renders it non-copyleft. The Creative Commons SA licence, in contrast, has no such problems. It is by any objective measure the superior licence; however, we really should license Wikibooks disjunctively with the GNU FDL, so that books can borrow the substantial material from Wikipedia if useful. ^_^ -- Toby

Jimmy Wales wrote: No, this is not what we will be doing (under my suggestion). If a textbook (like a cookbook would) takes content from Wikipedia, then it must license those contents under the GNU FDL alone. It obviously can't license them under a disjunctive licence; that would be a blatant violation of the GNU FDL, which says that only the GNU FDL can be used. OTOH, if a textbok (like any math book would) doesn't take content from WP, then it can use CC SA, or a disjunctive licence, or whatever it likes. My argument that you quoted above is about this situation. To be sure. One thing to consider is when material is different enough that it can belong to different licences (potentially), in case one wants to borrow from Wikipedia and one doesn't. This would be less a matter of distinction between material covered than the appropriate style of explanation for the relevant audience. For example, both a physics text and a math text might discuss vectors. But the physics explanation wouldn't be rigorous enough for the math text, and the math explanation wouldn't have the right sort of applications for the physics text. Anything borrowed would need to be rewritten -- in which case, copyright and licence issues don't apply. Similarly, a chemistry text and a cookbook might both discuss caramelisation, but in very different ways for different purposes, with no sharing of text. OTOH, the physics and chemistry texts might well want to borrow, not just information, but entire chunks of text with only minor changes -- especially given the modular nature of textbooks that's been proposed here, where different textbooks might share the exact same module. IMO, only the cookbook (of these examples) is likely to want WP text, so only it would need to change its licence from a disjunction to GNU FDL. Still, I may be wrong about the science books, since I'm not very familiar with either Wikipedia's material or the real needs of such textbooks. OTOH, a math textbook would need to rewrite every WP article it uses, and would probably just consider WP one more source of information. We'd also have to write code to handle all of this, but we need to redo all of the code anyway for the modules. This is exactly what I propose. This is a disjunctive licence. It is indeed too late for Wikipedia, AFAICT, but not for Wikibooks -- unless a Wikibook borrows from WP, in which case the disjunctive licence allows the project to switch over. If mav ends up being entirely right, then every project will borrow from WP but never from anything non-GNU, in which case everything will eventually be under the GNU FDL anyway. But I don't think that mav is right, certainly not for math books. -- Toby