GNU General Public License

Copyright (C) 1989, 1991 Free Software Foundation, Inc.
675 Mass Ave, Cambridge, MA 02139, USA

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.

Version 2, June 1991

• Preamble
• Terms and conditions for copying, distribution and modification
• Appendix: How to Apply These Terms to Your New Programs