Z:gnu-www-ja-license-list--49cd57-Some countries allow authors t/en

Some countries allow authors to put code in the public domain, but that requires explicit action. If you wish to do that, the method we recommend is to use CC0, which also works in other countries by putting on a license that is more or less equivalent to public domain. However, in most cases it is  better to copyleft your code to assure that freedom reaches all users of the code.