PyMod source code is licensed under the GNU General Public License, version 2
or (at your option) any later version.

In addition, as a special exception, the authors give permission to link the
code of this program with the Half-Life Game Engine ("HL Engine") and Modified
Game Libraries ("MODs") developed by Valve, L.L.C ("Valve"). You must obey the
GNU General Public License in all respects for all of the code used other than
the HL Engine and MODs from Valve. If you modify this program, you may extend
this exception to your version, but you are not obligated to do so. If you do
not wish to do so, delete this exception statement from your version.
