path: root/docs/fdl.md

## GNU 自由文档许可证

> 本版本由 Leo-Hong (leohca (at) yahoo.com) 翻译整理。 源网页：<http://www.thebigfly.com/gnu/FDLv1.3/>。

这是一份 GNU 自由文档许可证非正式的中文翻译。它并非由自由软件基金会所发表，亦非使用 GNU 自由文档许可证的文件的法定发布条款─只有 [GNU 自由文档许可证英文原文](http://www.gnu.org/licenses/fdl.html)的版本始具有此等效力。然而，我们希望这份翻译能帮助中文的使用者更了解 GNU 自由文档许可证。 

This is an unofficial translation of the GNU Free Documentation License into Chinese. It was not published by the Free Software Foundation, and does not legally state the distribution terms for documents that uses the GNU FDL--only [the original English text of the GNU FDL](http://www.gnu.org/licenses/fdl.html) does that. However, we hope that this translation will help Chinese speakers understand the GNU FDL better.

### GNU 自由文档许可证

第1.3版, 2008年11月

著作权所有 (C) 2000,2001,2002,2007,2008 Free Software Foundation, Inc.<http://fsf.org/></font>

允许每个人复制和发布本许可证文件的完整副本，  
但不允许对它进行任何修改。

### 0. 导言

本许可证的目的在于作为一种手册、教科书或其它的具有功能性的有用文件获得自由：确保每一个人都具有复制和重新发布它的有效自由，而不论是否作出修改，也不论其是否具有商业行为。其次，本许可证保存了作者以及出版者由于他们的工作而 得到 名誉的方式，同时也不被认为应该对其他人所作出的修改而担负责任。

本许可证是一种“copyleft”，这表示文件的衍生作品本身必须具有相同的自由涵义。它补足了GNU 公共通用许可证——一种为了自由软件而设计的“copyleft”许可证。

我们设计了本许可证是为了将它使用到自由软件的使用手册上，因为自由软件需要自由的文档：一种自由的程序应该提供与此软件具有相同的自由的使用手册。但是本许可证并不被限制在软件使用手册的应用上；它可以被用于任何以文字作基础的作品，而不论其主题内容，或者它是否是一个被出版的印刷书籍。我们建议本许可证主要应用在以使用说明或提供参考作为目的的作品上。

### 1. 效力与定义

本许可证的效力在于任何媒体中的任何的使用手册或其它作品，只要其中包含由版权所有人所指定的声明，说明它可以在本许可证的条款下被发布。这样的一份声明提供了全球范围内的,免版税的和没有期限的许可，在此所陈述条件下使用那个作品。以下所称的文件，指的是任何像这样的使用手册或作品。公众中的任何成员都是被许可人，并且称作为你。如果你以一种需要在版权法下取得允许的方式进行复制、修改或发布作品，你就接受了这项许可。

“修改版本”指的是任何包含文件或是它的其中一部份，不论是逐字的复制或是经过修正，或翻译成其它语言的任何作品。

“次要章节”是一个具名的附录，或是文件的本文之前内容的章节，专门用来处理文件的出版者或作者，与文件整体主题(或其它相关内容)的关系，并且不包含任何可以直接落入那个整体主题的内容。(因此，如果文件的部分内容是作为数学教科书，那么其次要章节就可以不用来解释任何数学。)它的关系可以是与主题相关的历史连接，或是与其相关的法律、商业、哲学、伦理道德或政治立场。

“不变章节”是标题已被指定的某些次要章节，在一个声明了是以本许可证加以发行的文件中，依此作为不变章节。如果一个章节并不符合上述有关于次要的定义时，则它并不允许被指定为不变。文件可以不包含不变章节。如果文件并没有指出任何不变章节，那么就是没有。

“封面文字”是某些被加以列出的简短文字段落，在一个声明了是以本许可证加以发行的文件中，依此作为前封面文字或后封面文字。前封面文字最多可以包含 5 个单词，后封面文字最多可以包含 25 个单词。

文件的”透明”拷贝指的是一份机器可读的拷贝，它以一种一般公众可以取得其规格说明的格式来表现，适合于直接用一般文字编辑器、一般点阵图像程序用于由图元像素构成的影像或一些可以广泛取得的绘图程序用于由向量绘制的图形直接地进行修订；并且适合于输入到文字格式化程式，或是可以自动地转换到适合于输入到文字格式化程序的各种格式。一份以透明以外的档案格式所构成的拷贝，其标记或缺少标记，若是被安排成用来挫折或是打消读者进行其后续的修改，则此拷贝并非透明。一种影像格式，如果仅仅是用来充斥文本的资料量时，就不是透明的。一个不是透明的拷贝被称为混浊。

透明拷贝适合格式的例子包括有：没有标记的纯 ASCII、Texinfo 输入格式、LaTeX 输入格式、使用可以公开取得其 DTD 的 SGML 或 XML、合乎标准的简单 HTML、PostScript 或 PDF。透明影像格式的例子有 PNG、XCF 和 JPG 。混浊格式包括只能够以私人文书处理器阅读以及编辑的私人格式、DTD 以及或处理工具不能够一般地加以取得的 SGML 或 XML、以及由某些文书处理器只是为了输出的目的而做出的，由机器制作的 HTML、PostScript 或 PDF 。

标题页对一本印刷书籍来说，指的是标题页本身，以及所需要用来容纳本许可证必须出现在标题页的易读内容的，如此的接续数页。对于并没有任何如此页面的作品的某些格式，标题页指的是本文主体开始之前作品标题最显着位置的文字。

出版者指的是把那些文本副本发布给公众的任何人或实体。

一个标题为 XYZ的章节指的是文件的一个具名的次要单元，其标题精确地为 XYZ 或是将 XYZ 包含在跟着翻译为其它语言的 XYZ 文字后面的括号内——这里 XYZ 代表的是名称于下提及的特定章节，像是感谢、贡献、背书或历史。当你修改文件时，给像这样子的章节保存其标题指的是，它保持为一个根据这个定义的标题为 XYZ的章节。

文件可以在用来陈述本许可证效力及于文件的声明后，包括担保放弃。这些担保放弃被考虑为以提及的方式，包括在本许可证中，但是只被看作为放弃担保之用：任何这些担保放弃可能会有的其它暗示都是无效的，并且也对本许可证的含义没有影响。

以下是有关复制、发布及修改的明确条款及条件。

### 2. 逐字的复制

你可以复制或发布文件于任何媒体，而不论其是否具有商业买卖行为，其条件为具有本许可证、版权声明和许可声明，说明本许可证效力于文件的所有重制拷贝，并且你没有增加任何其它条件到本许可证的条件中。你不可以使用技术手段，来妨碍或控制你所制作或发布的拷贝阅读或进一步的发布。然而，你可以接受补偿以作为拷贝的交换。如果你发布了数量足够大的拷贝，你也必须遵循第三条的条件。

你也可以在上述的相同条件下借出拷贝，并且你可以公开地陈列拷贝。

### 3. 大量地复制

如果你出版文件的印刷拷贝或者通常具有印刷封面的媒体的拷贝，数量上超过一百个单位，而且文件许可声明要求有封面文字，那么你必须将这些拷贝附上清楚且易读的文字：前封面文字于前封面上、后封面文字于后封面上。这两种封面必须清楚易读地辨认出，你是这些拷贝的出版者。前封面文字必须展示完整的标题，而标题的文字应当同等地显著可见。你可以增加额外的内容于封面上。仅在封面作出改变的复制，只要它们保存了文件的标题，并且满足了这些条件，可以在其它方面被看作为逐字的复制。

如果对于任意一个封面所需要的文字，数量过于庞大以至于不能符合易读的原则，你应该在实际封面的最前面列出所能符合易读原则的内容，然后将剩下的接续在相邻的页面。

如果你出版或发布数量超过一百个单位文件的混浊拷贝，你必须与此混浊拷贝一起包含一份机器可读的透明拷贝，或是与一份混浊拷贝一起或其陈述一个电脑网络位址，使一般的网络使用公众具有存取权，可以使用公开标准的网络协定，下载一份文件的完全透明拷贝，此拷贝中并且没有增加额外的内容。如果你使用后面的选项，当你开始大量地发布混浊拷贝时，你必须采取合理的审慎步骤，以保证这个透明拷贝将会在发布的一开始就保持可供存取，直到你最后一次发布那个发行版的一份混浊拷贝给公众后，至少一年为止。以保证这个透明拷贝，将会在所陈述的位址保持如此的可存取性，直到你最后一次发布那个发行版直接或经由你的代理商或零售商的一份混浊拷贝给公众后，至少一年为止。

你被要求，但不是必须，在重新发布任何大数量的拷贝之前与文件的作者联络，给予他们提供你一份文件的更新版本的机会。

### 4. 修改

你可以在上述第二条和第三条的条件下，复制和发布文件的修改版本，其条件为你要精确地在本许可证下发布修改版本，且修改版本补足了文件的角色，从而允许修改版本的发布和修改权利给任何拥有它拷贝的人。另外，你必须在修改版本中做这些事：

**第一款、** 在标题页或在封面上使用，如果有与先前版本不同的文件，应该被列在文件的历史章节不同的标题。如果版本的原始出版者允许，你可以使用与某一个先前版本相同的标题。

**第二款、** 在修改版本的标题页上列出担负作者权的一个或多个人或实体作为作者，并且列出至少五位文件的主要作者。如果少于五位，则列出全部的主要作者，除非他们免除了你这个要求。

**第三款、** 在标题页陈述修改版本的出版者的名称作为出版者。

**第四款、** 保存文件的所有版权声明。

**第五款、** 为你的修改增加一个与其它版权声明相邻的适当的版权声明。

**第六款、** 在版权声明后面，以许可证附录所显示的形式，包括一个给予公众在本许可证条款下使用修改版本的许可声明。

**第七款、** 在那个许可声明中保存恒常章节和文件许可声明中必要封面文字的全部列表。

**第八款、** 包括一个未被改变的本许可证的副本。

**第九款、** 保存标题为历史的章节和其标题，并且增加一项至少陈述如同在标题页中所给的修改版本的标题、年份、新作者和出版者。如果在文件中没有标题为历史的章节，则制作出一个陈述如同在它的标题页中所给的文件的标题、年份、新作者和出版者，然后增加一项描述修改版本如前面句子所陈述的情形。

**第十款、** 如果有的话，保存在文件中为了给公众存取文件的透明拷贝，而给予的网络位址，以及同样地在文件中为了它所根据的先前版本，而给予的网络位址。这些可以被放置在历史章节。你可以省略一个在文件本身之前，已经至少出版了四年的作品的网络位址，或是如果它所参照的那个版本的原始出版者给予允许的情形下也可以省略它。

**第十一款、** 在任何标题为感谢或贡献的章节，保存章节的标题，并且在那章节保存到那时候为止，每一个贡献者的感谢以及或贡献的所有声色。

**第十二款、** 保存文件的所有恒常章节，于其文字以及标题皆不得变更。章节号码或其同等物并不被认为是章节标题的一部份。

**第十三款、** 删除任何标题为背书的章节。这样子的章节不可以被包括在修改版本中。

**第十四款、** 不要重新命名任何现存的章节，而使其标题为背书，或造成与任何恒常章节相冲突的标题。

**第十五款、** 保存任何的担保放弃。

如果修改版本包括新的本文之前内容的章节，或合乎作为次要章节的附录，并且没有包含复制自文件的内容，则你具有选择可以指定一些或全部这些章节为恒常的。要这样做，将它们的标题增加到在修改版本许可声明中的恒常章节列表中。这些标题必须可以和任何其它章节标题加以区别。

你可以增加一个标题为背书的章节，其条件为它仅只包含由许多团体所提供的你的修改版本的背书——举例来说，同侪评审的说明，或本文已经被一个机构认可为一个标准的权威定义。

你可以增加一个作为前封面文字的最多五个字的段落，以及一个作为后封面文字的最多二十五个字的段落，到修改版本的封面文字列表的后面。前封面文字和后封面文字都只能有一个段落，可以经由任何一个实体，或经由任何一个实体所作出的安排而被加入。如果文件已经在同样的封面包括了封面文字——先前由你或由你所代表的相同实体所作出的安排而加入，则你不可以增加另外一个；但是你可以在先前出版者的明确允许下替换掉旧的。

文件的作者和出版者并不由此授权，而给予允许使用他们的名字以为了或经由声称或暗示任何修改版本背书为自己所应得的方式而获得名声的权利。

### 5. 组合文件

你可以在上述第四条的条款中对于修改版本的定义之下，将文件与其它在本许可证下发行的文件组合起来，其条件是你要在组合品中，包括所有原始文件的所有恒常章节，不做修改，同时在组合作品的许可声明中将它们全部列为恒常章节，并且你要保存它们所有的担保放弃。

组合作品只需包含本许可证的一份副本，并且重复的恒常章节可以仅以单一个拷贝来取代。如果名称重复但内容不同的恒常章节，则将任此章节的标题，以在它的后面增加的方式加以独特化，如果已知的话，于括号中指出那个章节的原始作者或出版者的名称，或是指定一个独特的号码。在此组合作品许可声明中恒常章节的列表中，对其章节标题也作出相同的调整。

在组合品中，你必须组合在不同原始文件中，标题为历史的任何章节，形成一个标题为历史的章节；同样组合任意标题为感谢或贡献的章节。你必须删除标题为背书的所有章节。

### 6. 文件的收集

你可以制作含有文件以及其它以本许可证发行文件的收集品，并且将本许可证对不同文件中的个别副本，以单一个包括在收集品的副本取代，其条件是你要遵循在其它方面，给予一个文件逐字复制的允许本许可证的规则。

你可以从这样的一个收集品中抽取出一份单一的文件，并且在本许可证下将它单独地发布，其条件是你要在抽取出的文件中插入本许可证的一份副本，并且在关于那份文件的逐字的复制的所有其它方面，遵循本许可证。

### 7. 独立作品的聚集

一个文件的编辑物，其中或附加于储存物或发布媒体的一册的，具有其它分别且独立的文件或作品的衍生品，如果经由编辑而产生的版权，并没有用来限制此编辑物使用者的法律权力，而超过了个别的作品所允许的，则被称为一个聚集品。当文件中包括一个聚集品，本许可证的效力并不仅在于此聚集品中的，于其本身并非文件的衍生作品的其它作品。

如果第三条的封面文字要求效力于这些文件的拷贝，并且文件的篇幅少于整个聚集品的一半，则文件的封面文字可以被放在只围绕着文件，并于聚集品内部的封面或是电子的封面同等物上，如果文件是以电子的形式出现的话。否则它们必须出现在绕着整个聚集品的印刷封面上。

### 8. 翻译

翻译被认为一种修改，因此你可以在第四条的条款下发布文件的翻译。用翻译更换恒常章节需要取得版权所有者的特别允许，但是你可以包括部份或所有恒常章节的翻译，使其附加到这些恒常章节的原始版本之中。你可以包括本许可证、文件中的所有许可声明和任何的担保放弃的翻译，其条件为你也必须包括本许可证的原始英文版本，以及这些声明与放弃的原始版本。如果发生翻译与本许可证、声明或放弃的原始版本有任何的不同意时，将以原始版本为准。

如果在文件中的章节被标题为感谢、贡献或历史，则保存标题第一条的必要条件第四条，典型上将会需要去更动实际的标题。

### 9. 终止

你不可以复制、修改、在本许可证下再设定额外条件的次授权或发布文件，除非明白地表示是在本许可证所规范的条件下进行。任何其它的复制、修改、在本许可证下再设定额外条件的次授权、或发布文件的意图都是无效的，并且将会自动地终止你在本许可证下所被保障的权利。

然而，如果你终止所有违反本许可证的行为，特定版权所有人会暂时恢复你的授权直到此版权所有者明确并最终地终止你的授权。或者特定版权所有人永久地恢复你的授权如果此版权所有人在停止违反授权后的60天内没有通过合理的方式通知你违反授权。

此外，此版权所有者用一些合理的方式通知你违反了授权规定，也是你第一次从此版权所有者收到违反授权的通知，并且你在收到通知后的30天内终止了这种行为，那么此版权所有者会永久地恢复你的授权。

你的权利在此章节的终止并不代表终止得到你的拷贝和权利的当事人的授权。如果你的权利被终止而没有被永久性地恢复，那么你将没有任何权利去使用此章节的全部或部分资料和资料的拷贝。

### 10. 本许可证的未来改版

自由软件基金会可能偶尔会出版自由文档许可证的新修订过的版本。这种新版本在精神上将会类似于现在的版本，但在细节上可能会有不同，以对应新的问题或相关的事。请见 http://www.gnu.org/copyleft/。

本许可证的任何版本都被指定一个可供区别的版本号码。如果文件指定一个效力于它的特定号码版本的本许可证或任何以后的版本，你就具有选择遵循指定的版本，或任何已经由自由软件基金会出版的后来版本并且不是草稿的条款和条件。如果文件并没有指定一个本许可证的版本号码，你就可以选择任何一个曾由自由软件基金会所出版不是草稿的版本。如果文件指定一个代理能够决定本许可证未来的那一种版本可以用，而且还指定代理公开声明如果你接受一种版本你将会永久地被授权为文本选择此版本的权利。

### 11. 重新授权

“MMC 网站”是指任何发布有著作版权作品的网站服务器，也为任何人提供卓越的设施去编辑一些作品。任何人都可编辑的一种公众维基就是这种服务器的一个例子。包含在这个网站的”MMC”是指任何一套在MMC网站上发布的具有著作版权的作品。

“CC-BY-SA”是指 Creative Commons Attribution-Share Alike 3.0 许可证，它是被“知识共享组织” 颁布的，“知识共享组织” 是一家非赢利性的，在圣弗朗西斯科，加利福尼亚具有重要的商业地位的组织。 而且未来的“copyleft”版本的许可证也是被同一个组织发布的。

“合并”是指以整体或作为另一个文本的部分发布或重新发布一个文本。

MMC有重新授权的资格，如果它是在MMC下授权；或者所有的作品首次发布并非在MMC下授权，后来以整体或部分合并到MMC下，它们没有覆盖性文本或不变的章节并且在2008年11月1日之前合并的。

那么MMC网站的操作者会在2009年8月1日之前的任何时间在同一网站重新发布包含在这一网站的MMC是经过CC-BY-SA 授权的，只要那个MMC有资格重新授权。

### 许可证附录：如何使用本许可证用于你的文件

为使用本许可证成为你撰写成的一份文件，必须在文件中包括本许可证的一份复本，以及标题页的后面包括许可声明：

````
Copyright (c) YEAR YOUR NAME. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".

````

如果你有恒常章节、前封面文字和后封面文字，请将with... Texts这一行以这些文本取代：

````
with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
````

如果你有不具封面文字的恒常章节，或一些其它这三者的组合，将可选择的二项合并以符合实际情形。

如果你的文件中包含有并非微不足道的程序码范例，我们建议这些范例平行地在你的自由软件授权选择下，比如以 GNU General Public License 的自由软件授权来发布，从而允许它们作为自由软件而使用。

**因为本书是基于 GNU FPL 许可证发布的，所以下面附加 FDL 许可证的英文原版，同时亦可与前面中文翻译版共同帮助理解。特此注明。**

### GNU Free Documentation License {#gnu-free-documentation-license .chapter}

Version 1.3, 3 November 2008

> Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc. http://fsf.org/
> Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.

1.  **PREAMBLE**

    The purpose of this License is to make a manual, textbook, or other
    functional and useful document *free* in the sense of freedom: to
    assure everyone the effective freedom to copy and redistribute it,
    with or without modifying it, either commercially
    or noncommercially. Secondarily, this License preserves for the
    author and publisher a way to get credit for their work, while not
    being considered responsible for modifications made by others.

    This License is a kind of “copyleft”, which means that derivative
    works of the document must themselves be free in the same sense. It
    complements the GNU General Public License, which is a copyleft
    license designed for free software.

    We have designed this License in order to use it for manuals for
    free software, because free software needs free documentation: a
    free program should come with manuals providing the same freedoms
    that the software does. But this License is not limited to software
    manuals; it can be used for any textual work, regardless of subject
    matter or whether it is published as a printed book. We recommend
    this License principally for works whose purpose is instruction
    or reference.

2.  **APPLICABILITY AND DEFINITIONS**

    This License applies to any manual or other work, in any medium,
    that contains a notice placed by the copyright holder saying it can
    be distributed under the terms of this License. Such a notice grants
    a world-wide, royalty-free license, unlimited in duration, to use
    that work under the conditions stated herein. The “Document”, below,
    refers to any such manual or work. Any member of the public is a
    licensee, and is addressed as “you”. You accept the license if you
    copy, modify or distribute the work in a way requiring permission
    under copyright law.

    A “Modified Version” of the Document means any work containing the
    Document or a portion of it, either copied verbatim, or with
    modifications and/or translated into another language.

    A “Secondary Section” is a named appendix or a front-matter section
    of the Document that deals exclusively with the relationship of the
    publishers or authors of the Document to the Document’s overall
    subject (or to related matters) and contains nothing that could fall
    directly within that overall subject. (Thus, if the Document is in
    part a textbook of mathematics, a Secondary Section may not explain
    any mathematics.) The relationship could be a matter of historical
    connection with the subject or with related matters, or of legal,
    commercial, philosophical, ethical or political position
    regarding them.

    The “Invariant Sections” are certain Secondary Sections whose titles
    are designated, as being those of Invariant Sections, in the notice
    that says that the Document is released under this License. If a
    section does not fit the above definition of Secondary then it is
    not allowed to be designated as Invariant. The Document may contain
    zero Invariant Sections. If the Document does not identify any
    Invariant Sections then there are none.

    The “Cover Texts” are certain short passages of text that are
    listed, as Front-Cover Texts or Back-Cover Texts, in the notice that
    says that the Document is released under this License. A Front-Cover
    Text may be at most 5 words, and a Back-Cover Text may be at most
    25 words.

    A “Transparent” copy of the Document means a machine-readable copy,
    represented in a format whose specification is available to the
    general public, that is suitable for revising the document
    straightforwardly with generic text editors or (for images composed
    of pixels) generic paint programs or (for drawings) some widely
    available drawing editor, and that is suitable for input to text
    formatters or for automatic translation to a variety of formats
    suitable for input to text formatters. A copy made in an otherwise
    Transparent file format whose markup, or absence of markup, has been
    arranged to thwart or discourage subsequent modification by readers
    is not Transparent. An image format is not Transparent if used for
    any substantial amount of text. A copy that is not “Transparent” is
    called “Opaque”.

    Examples of suitable formats for Transparent copies include plain
    ASCII without markup, Texinfo input format, LaTeX input format, SGML
    or XML using a publicly available DTD, and standard-conforming
    simple HTML, PostScript or PDF designed for human modification.
    Examples of transparent image formats include PNG, XCF and JPG.
    Opaque formats include proprietary formats that can be read and
    edited only by proprietary word processors, SGML or XML for which
    the DTD and/or processing tools are not generally available, and the
    machine-generated HTML, PostScript or PDF produced by some word
    processors for output purposes only.

    The “Title Page” means, for a printed book, the title page itself,
    plus such following pages as are needed to hold, legibly, the
    material this License requires to appear in the title page. For
    works in formats which do not have any title page as such, “Title
    Page” means the text near the most prominent appearance of the
    work’s title, preceding the beginning of the body of the text.

    The “publisher” means any person or entity that distributes copies
    of the Document to the public.

    A section “Entitled XYZ” means a named subunit of the Document whose
    title either is precisely XYZ or contains XYZ in parentheses
    following text that translates XYZ in another language. (Here XYZ
    stands for a specific section name mentioned below, such as
    “Acknowledgements”, “Dedications”, “Endorsements”, or “History”.) To
    “Preserve the Title” of such a section when you modify the Document
    means that it remains a section “Entitled XYZ” according to
    this definition.

    The Document may include Warranty Disclaimers next to the notice
    which states that this License applies to the Document. These
    Warranty Disclaimers are considered to be included by reference in
    this License, but only as regards disclaiming warranties: any other
    implication that these Warranty Disclaimers may have is void and has
    no effect on the meaning of this License.

3.  **VERBATIM COPYING**

    You may copy and distribute the Document in any medium, either
    commercially or noncommercially, provided that this License, the
    copyright notices, and the license notice saying this License
    applies to the Document are reproduced in all copies, and that you
    add no other conditions whatsoever to those of this License. You may
    not use technical measures to obstruct or control the reading or
    further copying of the copies you make or distribute. However, you
    may accept compensation in exchange for copies. If you distribute a
    large enough number of copies you must also follow the conditions in
    section 3.

    You may also lend copies, under the same conditions stated above,
    and you may publicly display copies.

4.  **COPYING IN QUANTITY**

    If you publish printed copies (or copies in media that commonly have
    printed covers) of the Document, numbering more than 100, and the
    Document’s license notice requires Cover Texts, you must enclose the
    copies in covers that carry, clearly and legibly, all these Cover
    Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
    the back cover. Both covers must also clearly and legibly identify
    you as the publisher of these copies. The front cover must present
    the full title with all words of the title equally prominent
    and visible. You may add other material on the covers in addition.
    Copying with changes limited to the covers, as long as they preserve
    the title of the Document and satisfy these conditions, can be
    treated as verbatim copying in other respects.

    If the required texts for either cover are too voluminous to fit
    legibly, you should put the first ones listed (as many as
    fit reasonably) on the actual cover, and continue the rest onto
    adjacent pages.

    If you publish or distribute Opaque copies of the Document numbering
    more than 100, you must either include a machine-readable
    Transparent copy along with each Opaque copy, or state in or with
    each Opaque copy a computer-network location from which the general
    network-using public has access to download using public-standard
    network protocols a complete Transparent copy of the Document, free
    of added material. If you use the latter option, you must take
    reasonably prudent steps, when you begin distribution of Opaque
    copies in quantity, to ensure that this Transparent copy will remain
    thus accessible at the stated location until at least one year after
    the last time you distribute an Opaque copy (directly or through
    your agents or retailers) of that edition to the public.

    It is requested, but not required, that you contact the authors of
    the Document well before redistributing any large number of copies,
    to give them a chance to provide you with an updated version of
    the Document.

5.  **MODIFICATIONS**

    You may copy and distribute a Modified Version of the Document under
    the conditions of sections 2 and 3 above, provided that you release
    the Modified Version under precisely this License, with the Modified
    Version filling the role of the Document, thus licensing
    distribution and modification of the Modified Version to whoever
    possesses a copy of it. In addition, you must do these things in the
    Modified Version:

    1.  Use in the Title Page (and on the covers, if any) a title
        distinct from that of the Document, and from those of previous
        versions (which should, if there were any, be listed in the
        History section of the Document). You may use the same title as
        a previous version if the original publisher of that version
        gives permission.
    2.  List on the Title Page, as authors, one or more persons or
        entities responsible for authorship of the modifications in the
        Modified Version, together with at least five of the principal
        authors of the Document (all of its principal authors, if it has
        fewer than five), unless they release you from this requirement.
    3.  State on the Title page the name of the publisher of the
        Modified Version, as the publisher.
    4.  Preserve all the copyright notices of the Document.
    5.  Add an appropriate copyright notice for your modifications
        adjacent to the other copyright notices.
    6.  Include, immediately after the copyright notices, a license
        notice giving the public permission to use the Modified Version
        under the terms of this License, in the form shown in the
        Addendum below.
    7.  Preserve in that license notice the full lists of Invariant
        Sections and required Cover Texts given in the Document’s
        license notice.
    8.  Include an unaltered copy of this License.
    9.  Preserve the section Entitled “History”, Preserve its Title, and
        add to it an item stating at least the title, year, new authors,
        and publisher of the Modified Version as given on the
        Title Page. If there is no section Entitled “History” in the
        Document, create one stating the title, year, authors, and
        publisher of the Document as given on its Title Page, then add
        an item describing the Modified Version as stated in the
        previous sentence.
    10. Preserve the network location, if any, given in the Document for
        public access to a Transparent copy of the Document, and
        likewise the network locations given in the Document for
        previous versions it was based on. These may be placed in the
        “History” section. You may omit a network location for a work
        that was published at least four years before the Document
        itself, or if the original publisher of the version it refers to
        gives permission.
    11. For any section Entitled “Acknowledgements” or “Dedications”,
        Preserve the Title of the section, and preserve in the section
        all the substance and tone of each of the contributor
        acknowledgements and/or dedications given therein.
    12. Preserve all the Invariant Sections of the Document, unaltered
        in their text and in their titles. Section numbers or the
        equivalent are not considered part of the section titles.
    13. Delete any section Entitled “Endorsements”. Such a section may
        not be included in the Modified Version.
    14. Do not retitle any existing section to be Entitled
        “Endorsements” or to conflict in title with any
        Invariant Section.
    15. Preserve any Warranty Disclaimers.

    If the Modified Version includes new front-matter sections or
    appendices that qualify as Secondary Sections and contain no
    material copied from the Document, you may at your option designate
    some or all of these sections as invariant. To do this, add their
    titles to the list of Invariant Sections in the Modified Version’s
    license notice. These titles must be distinct from any other
    section titles.

    You may add a section Entitled “Endorsements”, provided it contains
    nothing but endorsements of your Modified Version by various
    parties—for example, statements of peer review or that the text has
    been approved by an organization as the authoritative definition of
    a standard.

    You may add a passage of up to five words as a Front-Cover Text, and
    a passage of up to 25 words as a Back-Cover Text, to the end of the
    list of Cover Texts in the Modified Version. Only one passage of
    Front-Cover Text and one of Back-Cover Text may be added by (or
    through arrangements made by) any one entity. If the Document
    already includes a cover text for the same cover, previously added
    by you or by arrangement made by the same entity you are acting on
    behalf of, you may not add another; but you may replace the old one,
    on explicit permission from the previous publisher that added the
    old one.

    The author(s) and publisher(s) of the Document do not by this
    License give permission to use their names for publicity for or to
    assert or imply endorsement of any Modified Version.

6.  **COMBINING DOCUMENTS**

    You may combine the Document with other documents released under
    this License, under the terms defined in section 4 above for
    modified versions, provided that you include in the combination all
    of the Invariant Sections of all of the original documents,
    unmodified, and list them all as Invariant Sections of your combined
    work in its license notice, and that you preserve all their
    Warranty Disclaimers.

    The combined work need only contain one copy of this License, and
    multiple identical Invariant Sections may be replaced with a
    single copy. If there are multiple Invariant Sections with the same
    name but different contents, make the title of each such section
    unique by adding at the end of it, in parentheses, the name of the
    original author or publisher of that section if known, or else a
    unique number. Make the same adjustment to the section titles in the
    list of Invariant Sections in the license notice of the
    combined work.

    In the combination, you must combine any sections Entitled “History”
    in the various original documents, forming one section Entitled
    “History”; likewise combine any sections Entitled
    “Acknowledgements”, and any sections Entitled “Dedications”. You
    must delete all sections Entitled “Endorsements.”

7.  **COLLECTIONS OF DOCUMENTS**

    You may make a collection consisting of the Document and other
    documents released under this License, and replace the individual
    copies of this License in the various documents with a single copy
    that is included in the collection, provided that you follow the
    rules of this License for verbatim copying of each of the documents
    in all other respects.

    You may extract a single document from such a collection, and
    distribute it individually under this License, provided you insert a
    copy of this License into the extracted document, and follow this
    License in all other respects regarding verbatim copying of
    that document.

8.  **AGGREGATION WITH INDEPENDENT WORKS**

    A compilation of the Document or its derivatives with other separate
    and independent documents or works, in or on a volume of a storage
    or distribution medium, is called an “aggregate” if the copyright
    resulting from the compilation is not used to limit the legal rights
    of the compilation’s users beyond what the individual works permit.
    When the Document is included in an aggregate, this License does not
    apply to the other works in the aggregate which are not themselves
    derivative works of the Document.

    If the Cover Text requirement of section 3 is applicable to these
    copies of the Document, then if the Document is less than one half
    of the entire aggregate, the Document’s Cover Texts may be placed on
    covers that bracket the Document within the aggregate, or the
    electronic equivalent of covers if the Document is in
    electronic form. Otherwise they must appear on printed covers that
    bracket the whole aggregate.

9.  **TRANSLATION**

    Translation is considered a kind of modification, so you may
    distribute translations of the Document under the terms of
    section 4. Replacing Invariant Sections with translations requires
    special permission from their copyright holders, but you may include
    translations of some or all Invariant Sections in addition to the
    original versions of these Invariant Sections. You may include a
    translation of this License, and all the license notices in the
    Document, and any Warranty Disclaimers, provided that you also
    include the original English version of this License and the
    original versions of those notices and disclaimers. In case of a
    disagreement between the translation and the original version of
    this License or a notice or disclaimer, the original version
    will prevail.

    If a section in the Document is Entitled “Acknowledgements”,
    “Dedications”, or “History”, the requirement (section 4) to Preserve
    its Title (section 1) will typically require changing the
    actual title.

10. **TERMINATION**

    You may not copy, modify, sublicense, or distribute the Document
    except as expressly provided under this License. Any attempt
    otherwise to copy, modify, sublicense, or distribute it is void, and
    will automatically terminate your rights under this License.

    However, if you cease all violation of this License, then your
    license from a particular copyright holder is reinstated (a)
    provisionally, unless and until the copyright holder explicitly and
    finally terminates your license, and (b) permanently, if the
    copyright holder fails to notify you of the violation by some
    reasonable means prior to 60 days after the cessation.

    Moreover, your license from a particular copyright holder is
    reinstated permanently if the copyright holder notifies you of the
    violation by some reasonable means, this is the first time you have
    received notice of violation of this License (for any work) from
    that copyright holder, and you cure the violation prior to 30 days
    after your receipt of the notice.

    Termination of your rights under this section does not terminate the
    licenses of parties who have received copies or rights from you
    under this License. If your rights have been terminated and not
    permanently reinstated, receipt of a copy of some or all of the same
    material does not give you any rights to use it.

11. **FUTURE REVISIONS OF THIS LICENSE**

    The Free Software Foundation may publish new, revised versions of
    the GNU Free Documentation License from time to time. Such new
    versions will be similar in spirit to the present version, but may
    differ in detail to address new problems or concerns. See
    <http://www.gnu.org/copyleft/>.

    Each version of the License is given a distinguishing
    version number. If the Document specifies that a particular numbered
    version of this License “or any later version” applies to it, you
    have the option of following the terms and conditions either of that
    specified version or of any later version that has been published
    (not as a draft) by the Free Software Foundation. If the Document
    does not specify a version number of this License, you may choose
    any version ever published (not as a draft) by the Free
    Software Foundation. If the Document specifies that a proxy can
    decide which future versions of this License can be used, that
    proxy’s public statement of acceptance of a version permanently
    authorizes you to choose that version for the Document.

12. **RELICENSING**

    “Massive Multiauthor Collaboration Site” (or “MMC Site”) means any
    World Wide Web server that publishes copyrightable works and also
    provides prominent facilities for anybody to edit those works. A
    public wiki that anybody can edit is an example of such a server. A
    “Massive Multiauthor Collaboration” (or “MMC”) contained in the site
    means any set of copyrightable works thus published on the MMC site.

    “CC-BY-SA” means the Creative Commons Attribution-Share Alike 3.0
    license published by Creative Commons Corporation, a not-for-profit
    corporation with a principal place of business in San Francisco,
    California, as well as future copyleft versions of that license
    published by that same organization.

    “Incorporate” means to publish or republish a Document, in whole or
    in part, as part of another Document.

    An MMC is “eligible for relicensing” if it is licensed under this
    License, and if all works that were first published under this
    License somewhere other than this MMC, and subsequently incorporated
    in whole or in part into the MMC, (1) had no cover texts or
    invariant sections, and (2) were thus incorporated prior to November
    1, 2008.

    The operator of an MMC Site may republish an MMC contained in the
    site under CC-BY-SA on the same site at any time before August 1,
    2009, provided the MMC is eligible for relicensing.

#### ADDENDUM: How to use this License for your documents {#addendum-how-to-use-this-license-for-your-documents .heading}

To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:

```
Copyright (C)  year  your name.  
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or  any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License"".
```

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
replace the “with…Texts.” line with this:

```
with the Invariant Sections being list their titles, with the Front-Cover Texts being list, and with the Back-Cover Texts being list.
```

If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.

If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of free
software license, such as the GNU General Public License, to permit
their use in free software.