We are using the GNU public licence (GPL) for this project. Here is the summary included with the code.
Voting Systems Toolbox
Copyright (C) 2001 Roy Ward
Voting Systems Toolbox is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License.
Voting Systems Toolbox is distributed in the hope that it will 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.
You should have received a copy of the GNU General Public License along with Voting Systems Toolbox; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
The full text of the GPL is available here or here.