Z:gnu-www-ja-gpl-2.0-faq--237fd8-From time to time, at interval/en

From time to time, at intervals of years, we change the GPL&mdash;sometimes to clarify it, sometimes to permit certain kinds of use not previously permitted, and sometimes to tighten up a requirement. (The last change was in 1991.) Using this &ldquo;indirect pointer&rdquo; in each program makes it possible for us to change the distribution terms on the entire collection of GNU software, when we update the GPL.