User manual

158

GNU GENERAL PUBLIC LICENSE

Version 3, 29 June 2007

Everyone is permitted to copy and distribute verbatim copies of this license

document, but changing it is not allowed.

Preamble

The GNU General Public License is a free, copyleft license for software and other

kinds of works.

The licenses for most software and other practical works are designed to take

away your freedom to share and change the works. By contrast, the GNU General

Public License is intended to guarantee your freedom to share and change all

versions of a program--to make sure it remains free software for all its users. We,

the Free Software Foundation, use the GNU General Public License for most of our

software; it applies also to any other work released this way by its authors. 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 them 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 prevent others from denying you these rights or

asking you to surrender the rights. Therefore, you have certain responsibilities if

you distribute copies of the software, or if you modify it: responsibilities to respect

the freedom of others.

For example, if you distribute copies of such a program, whether gratis or for a fee,

you must pass on to the recipients the same freedoms that you received. You

must make sure that they, too, receive or can get the source code. And you must

show them these terms so they know their rights.