http://en.wikipedia.org/wiki/GNU_General_Public_License This WikiPedia.org web page explains the GNU Public License for software development allowing unrestricted reuse of free and open source code with that license. As of April 2010, there are 3 versions of the GNU P/L. In this respect, the GNU P/L is for computer source code what the Creative Commons Copyright is for hard-copy (in-print) and Internet digital content.