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GNU General Public Licence
EN
19. GNU General Public Licence
Version 2, June 1991
Copyright (C) 1989,
1991 Free Software Foundation, Inc.
51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA
Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.
Preamble
The licenses for most software are designed to take away your free-
dom to share and change it. By contrast, the GNU General Public Li-
cense is intended to guarantee your freedom to share and change
free software--to make sure the software is free for all its users. This
General Public License applies to most of the Free Software Founda-
tion‘s software and to any other program whose authors commit to
using it. (Some other Free Software Foundation software is covered
by the GNU Lesser General Public License instead.) You can apply it
to your programs, too.
When we speak of free software, we are referring to freedom, not
price. Our General Public Licenses are designed to make sure that
you have the freedom to distribute copies of free software (and
charge for this service if you wish), that you receive source code or
can get it if you want it, that you can change the software or use
pieces of it in new free programs; and that you know you can do
these things.
To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the
rights. These restrictions translate to certain responsibilities for you if
you distribute copies of the software, or if you modify it.
For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
