David Braverman <david@braverman.org> writes:

Um...a statement in a creative work that says "this work is in the public domain" generally *does* put it in the public domain. Anyone who owns property is free to give it away.

Actually, this is somewhat more dubious than most people think if you're in the US. US copyright statutes don't include a way for people to voluntarily place things into the public domain. Whether or not saying that something is in the public domain "works" or not is one of those things that copyright lawyers tend to argue about, and conservative ones will say don't do that because the legal status is ambiguous. Hence the Creative Commons CC-0 license and other such licenses that attempt to approximate the public domain without having that problem. It's quite possible that someone could say that something is in the public domain and then later change their mind and successfully enforce copyright, although there are obvious estoppel issues that would make it hard to get much in the way of damages or possibly even to enforce it. But in any event all that only really matters if the copyright holder wants to enforce copyright on something, which clearly isn't the case for the tz maintainers, so as Clive says it comes down to whether the data in the tz database really has the legal status that we all think it does. (Personally, my bet is that it's sufficiently factual that the specific rules aren't copyrightable, although of course things like naming choices and the supporting commentary all are.) -- Russ Allbery (rra@stanford.edu) <http://www.eyrie.org/~eagle/>