The Digraph3 modules' code sources are "free," this means that everyone is free to use them and free to redistribute them on certain conditions. The Digraph3 modules are not in the public domain; they are copyrighted and there are restrictions on their distribution as follows:
Copyright © 2006-2015 Raymond Bisdorff (University of Luxembourg)
These Python3 source codes are free software; you can redistribute them and/or modify them under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
These resources are distributed in the hope that they may be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose. See the GNU General Public License for more details.
Raymond Bisdorff, July 1, 2014