User manual

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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.