User manual

GNU GENERAL PUBLIC LICENSE

Version 2, June 1991

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

Everyone is perm itted to copy and distribute verbatim copies

of this license doc ument, but changing it is not allowed.

Preamble

The licenses for most software are designed to take awa y your freedom to share and change it.

By contrast, the GNU General Public L ic ense is intended to guarantee your freedom to share

and change free software--to make sure t he software is free for all its users. This General

Public License appl ies to most of the Free Software Foundati on's software and to any other

program whose authors commit to using it. (Some other Free Software F oundation 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 m ake sure that you have the freedom to distr ibute 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 s oftware, or if you modify it.

For example, if you dis tribute 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 m ust show them these terms so they know their rights.

We protect your ri ghts with two steps: ( 1) copyright the software, and (2) offer you this licens e

which gives you le gal permission to copy, distribute and/or modify the software.

Also, for each author's protection and ours, we want to make c ertain that everyone

understands that there is no warranty for this free software. If the software is modified by

someone else and passed on, we want its recipients to know that what they have is not the

original, so that any problems introduced by others will not reflect on the original authors'

reputations.

Finally, any free program is threatened constantly by software patents. We wish to avoid the

danger that redistributors of a free program will individually obtain patent l ic enses, in effect

making the program proprietary. To prevent this , we have made it clear that any patent must be

licensed for everyone's free use or not licensed at all.

The precise terms and conditions for copying, distribution and modification follow.