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Version 2, June 1991
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USA Everyone is p ermitted to copy an d distribute ve rbatim copies of this li cense document, bu t 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 sof tware is free for a ll its users. Th is General Publi c License applies to mos t of the Free
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apply it to your prog rams, too.
When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are
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To protect your right s, we need to make res trictions that fo rbid anyone to deny you t hese rights or to as k you
to surrender t he rights. These restrictio ns translate to cer tain responsibilities for you if you distribute copies of
the softwar e, or if you modify it .
For example, if you d istribute copi es of such a program, w hether gratis or fo r a fee, you must give the
recipients all t he rights that you hav e. You must make sure that t hey, too, receive or can get t he source code.
And you must show the m these terms so the y know their right s.
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Also, for each autho r’s protection a nd ours, we want to ma ke certain that ev eryone under stands that the re
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recipients to know that what they have is not the original, so that any problems introduced by others will not
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Finally, any free prog ram is threaten ed constantly by sof tware patent s. We wish to avoid the dange r that
redistribu tors of a free progr am will individua lly obtain patent li censes, in effect m aking the progr am
proprietar y. To prevent this, we have made i t clear that any paten t must be licensed for eve ryone’s free use or
not licensed at all.
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TERMS AND CONDI TIONS FOR COPYIN G, DISTRIB UTION AND MODIF ICATION
0. This Licen se applies to any progr am or other work whi ch contains a notice place d by the copyright holde r
saying it may be dist ributed under th e terms of this Gene ral Public License . The “Program”, bel ow, refers
to any such program o r work, and a “wor k based on the Progr am” means either th e Program or any
derivative wor k under copyright l aw: that is to say, a work cont aining the Progra m or a portion of it , either
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scope. The act of r unning the Progr am is not restr icted, and the ou tput from the Pr ogram is covered o nly if its
contents consti tute a work based o n the
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what the Progra m does.