GNU General Public License

Copyright (C) 1996  Robert Gentleman and Ross Ihaka
Copyright (C) 1999-2016 The R Core Team

this program 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; either version 2 of the License, or (at your option) any later version. This program 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.

A copy of the GNU General Public License is available at https://www.R-project.org/Licenses/