The MAME project as a whole is distributed under the terms of the `GNU General Public License, version 2 or later <http://opensource.org/licenses/GPL-2.0>`_ (GPL-2.0+), since it contains code made available under multiple GPL-compatible licenses. A great majority of files (over 90% including core files) are under the `BSD-3-Clause License <http://opensource.org/licenses/BSD-3-Clause>`_ and we would encourage new contributors to distribute files under this license.