66PreambleThe licenses for most software are designed to take awayyour freedom to share and change it. By contrast, theGNU General Public License is intended to guarantee yourfreedom to share and change free software--to make surethe software is free for all its users. This General PublicLicense applies to most of the Free Software Foundation’ssoftware and to any other program whose authors committo using it. (Some other Free Software Foundation softwareis covered by the GNU Lesser General Public Licenseinstead.) You can apply it to your programs, too.When we speak of free software, we are referring tofreedom, not price. Our General Public Licenses aredesigned to make sure that you have the freedom todistribute copies of free software (and charge for this serviceif you wish), that you receive source code or can get it if youwant it, that you can change the software or use pieces of itin new free programs; and that you know you can do thesethings.To protect your rights, we need to make restrictions thatforbid anyone to deny you these rights or to ask you tosurrender the rights. These restrictions translate to certainresponsibilities for you if you distribute copies of thesoftware, 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 allthe rights that you have. You must make sure that they, too,receive or can get the source code. And you must showthem these terms so they know their rights.We protect your rights with two steps: (1) copyright thesoftware, and (2) offer you this license which gives you legalpermission to copy, distribute and/or modify the software.Also, for each author’s protection and ours, we want tomake certain that everyone understands that there is nowarranty for this free software. If the software is modied bysomeone else and passed on, we want its recipients to knowthat what they have is not the original, so that any problemsintroduced by others will not reect on the original authors’reputations.Finally, any free program is threatened constantly bysoftware patents. We wish to avoid the danger thatredistributors of a free program will individually obtainpatent licenses, in effect making the program proprietary. Toprevent this, we have made it clear that any patent must belicensed for everyone’s free use or not licensed at all.The precise terms and conditions for copying, distributionand modication follow.TERMS AND CONDITIONS FOR COPYING,DISTRIBUTION AND MODIFICATIONThis License applies to any program or other work which0.contains a notice placed by the copyright holder saying itmay be distributed under the terms of this General PublicLicense. The “Program”, below, refers to any such programor work, and a “work based on the Program” means eitherthe Program or any derivative work under copyright law:that is to say, a work containing the Program or a portionof it, either verbatim or with modications and/or translatedinto another language. (Hereinafter, translation is includedwithout limitation in the term “modication”.) Each licenseeis addressed as “you”.Activities other than copying, distribution andmodication are not covered by this License; they areoutside its scope. The act of running the Program is notrestricted, and the output from the Program is coveredonly if its contents constitute a work based on theProgram (independent of having been made by runningthe Program). Whether that is true depends on what theProgram does.You may copy and distribute verbatim copies of the1.Program’s source code as you receive it, in any medium,provided that you conspicuously and appropriatelypublish on each copy an appropriate copyright noticeand disclaimer of warranty; keep intact all the noticesthat refer to this License and to the absence of anywarranty; and give any other recipients of the Program acopy of this License along with the Program.You may charge a fee for the physical act of transferringa copy, and you may at your option offer warrantyprotection in exchange for a fee.You may modify your copy or copies of the Program2.or any portion of it, thus forming a work based on theProgram, and copy and distribute such modications orwork under the terms of Section 1 above, provided thatyou also meet all of these conditions:You must cause the modied les to carry prominenta)notices stating that you changed the les and thedate of any change.You must cause any work that you distribute orb)publish, that in whole or in part contains or is derivedfrom the Program or any part thereof, to be licensedas a whole at no charge to all third parties under theterms of this License.If the modied program normally reads commandsc)interactively when run, you must cause it, whenstarted running for such interactive use in the mostordinary way, to print or display an announcementincluding an appropriate copyright notice and a noticethat there is no warranty (or else, saying that youprovide a warranty) and that users may redistributethe program under these conditions, and telling theuser how to view a copy of this License. (Exception: ifthe Program itself is interactive but does not normallyprint such an announcement, your work based on theProgram is not required to print an announcement.)GNU GENERAL PUBLIC LICENSEVersion 2, June 1991Copyright (C) 1989, 1991 Free Software Foundation, Inc.51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USAEveryone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.