Z:gnu-www-ja-rms-why-gplv3--336de9-First of all, it is important/en

First of all, it is important to note that upgrading is a choice. GPL version 2 will remain a valid license, and no disaster will happen if some programs remain under GPLv2 while others advance to GPLv3. These two licenses are incompatible, but that isn't a fundamental problem.