31.1. 附录A：GNU通用公共许可证（GUN GPL）

版本 2, 1991年6月

任何人都可以复制和分发本授权文件的完整副本，但不允许更改。

序言

大多数软件的许可证都是为了剥夺你分享和修改软件的自由而设计的。相比之下，GNU通用公共许可证旨在保障您共享和更改自由软件的自由，以确保软件对所有用户都是免费的。本通用公共许可证适用于自由软件基金会的大多数软件，以及其作者承诺使用它的任何其他程序。（一些其他的自由软件基金会软件被GNU库通用公共许可证所覆盖。）你也可以将它应用到你的程序中。

当我们谈到自由软件（free software）时，我们指的是自由而不是价格。我们的GNU通用公共许可证决意保证你有发布自由软件的自由（如果你愿意，你可以对此项服务收取一定的费用）；保证你能收到源程序或者在你需要时能够得到它；保证你能修改软件或将它的一部分用于新的自由软件；而且还保证你知道你能做这些事情。

为了保护你的权利，我们需要作出规定：禁止任何人不承认你的权利，或者要求你放弃这些权利。如果你修改了库或者发布了库的副本，这些规定就转化为你的责任。

例如，如果你发布这样一个软件的副本，不管是收费的还是免费的，你必须将你具有的一切权利给予你的接受者。你必须保证他们能收到或得到源程序。并且你必须将这些条款给他们看，使他们知道他们有这样的权利。

我们采取两项措施来保护你的权利：（1）给软件以版权保护。（2）给你提供许可证。它给你复制，发布和修改这些软件的法律许可。

同样，为了保护发布者，我们需要清楚地让每个人明白，自由库软件没有担保。如果由于其他某个人修改了库，并继续加以传播。我们需要它的接受者明白：他们所得到的并不是原来的版本。任何由其他人引入的任何问题，不应损害原作者的声誉。

最后，任何自由软件不断受到软件专利的威胁。我们希望避免这样的风险，自由软件的再发布者以个人名义获得专利许可证。从而在事实上将软件变为私有。为防止这一点，我们必须明确：任何专利必须以允许每个人自由使用为前提，否则就不准许有专利。

以下是关于复制、分发和修改的详细条款和条件。复制、分发和修改的条款和条件

This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The "Program", below, refers to any such program or work, and a "work based on the Program" means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term "modification".) Each licensee is addressed as "you".

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