Z:gnu-www-ja-gpl-2.0-faq--e75dbc-If a tighter requirement in a/en

If a tighter requirement in a new version of the GPL need not be obeyed for existing software, how is it useful? Once GPL version 3 is available, the developers of most GPL-covered programs will release subsequent versions of their programs specifying &ldquo;Version 3 of the GPL or any later version&rdquo;. Then users will have to follow the tighter requirements in GPL version 3, for subsequent versions of the program.