Z:gnu-www-ja-thegnuproject--1afe1a-For an effective copyleft, mod/en

For an effective copyleft, modified versions must also be free. This ensures that work based on ours becomes available to our community if it is published. When programmers who have jobs as programmers volunteer to improve GNU software, it is copyleft that prevents their employers from saying, &ldquo;You can't share those changes, because we are going to use them to make our proprietary version of the program.&rdquo;