User's Manual

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143

GNUGENERALPUBLICLICENSE

Version 2, June 1991

59 Temple Place, Suite 330, Boston, MA 02111-1307 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

freedom to share and change it. By contrast, the GNU General

Public License 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 Foundation’s software and to any other program

whose authors commit to using it. (Some other Free Software

Foundation software is covered by the GNU Library 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 you have. 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.