Z:gnu-www-ja-netscape-npl-old--c2a482-The lack of real copyleft is n/en

The lack of real copyleft is not a catastrophe; it does not make the software nonfree. For example, the XFree86 distribution terms do not try to use copyleft at all, yet XFree86 is free software nonetheless. BSD is also non-copylefted free software (although the BSD terms have a serious drawback and should not be imitated&mdash;if you want to release non-copylefted free software, please use the XFree86 terms instead). Netscape software can also be free software without being copylefted.