0. PREAMBLE
The general idea of copyleft is to use the copyright system to ensure that everyone who possesses a copy or a derivative of a certain work has the effective freedom to copy and redistribute it, with or without modifying it. A copyleft license gives you certain rights, above and beyond the meager rights copyright law allows you. For example, the GNU General Public License is a copyleft license designed for free software.
The GNU Project designed this, the GNU Free Documentation License, for use with documentation about free software. Copylefting the documentation for free software is particularly important because free software needs to come with documentation that gives users the same freedoms that the software gives them. However, this License can be used for any textual work, regardless of its subject matter, and regardless of whether it is released in the form of a printed book. For short works which become much larger if this License is added, we recommend simply putting them in the public domain.
1. APPLICABILITY AND DEFINITIONS
This License applies to any manual or other work that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. The "Manual", below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as "you".
A "Modified Version" of the Manual means any work containing the Manual 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 Manual that deals exclusively with relationship of certain parties to the Manual's overall subject (or to related matters) and contains nothing that could fall properly within that overall subject. The relationship could be a matter of historical connection with the subject or related matters, or a legal, philosophical, ethical or political position regarding them.
The "Invariant Sections" are certain Secondary Sections whose titles are designated, as those of Invariant Sections, in the notice that says that the Manual is released under this License.
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 Manual is released under this License.
A "Transparent" copy of the Manual means a machine-readable copy, represented in a format whose specification is available to the general public, whose contents can be viewed and edited directly and 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 has been designed to thwart or discourage subsequent modification by readers is not Transparent. 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 designed for human modification. Opaque formats include PostScript, PDF, 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 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.
2. VERBATIM COPYING
You may copy and distribute the Manual in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Manual 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.
You may also lend copies, under the same conditions stated above, and you may publicly display copies.
It is requested, but not required, that you contact the authors of the Manual well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Manual.
3. COPYING IN QUANTITY
If you publish printed copies of the Manual numbering more than 100, and the Manual'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 manual 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 Manual 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 publicly-accessible computer-network location containing a complete Transparent copy of the Manual, free of added material, which the general network-using public has access to download anonymously at no charge using public-standard network protocols. 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 six months after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public.
4. MODIFICATIONS
You may copy and distribute a Modified Version of the Manual 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 Manual, thus licensing use of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:
A. Entitle your Modified Version with the Manual's title, plus
some additional words (or a subtitle) stating that the version has
been modified, and distinguishing it from the Manual you started with.
(Additions to the title are not required if the original publisher
of the version you started with waives this requirement.)
B. Mention the Manual's title on the Title Page (and on the Covers, if any).
C. Mention on the Title Page at least one name of a person or entity
responsible for authorship of the modifications in the Modified
Version and/or publication of the Modified Version, and describe
that entity's relationship to the Modified Version. (This requirement
may be waived by the original publisher of the version you started with.)
D. Retain on the Title Page or its continuation the authors' and publishers'
names listed on the Manual's Title Page.
E. Preserve all the copyright notices of the Manual.
F. Add an appropriate copyright notice for your own work.
G. 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.
H. Preserve in that license notice the full lists of Invariant Sections
and required Cover Texts given in the Manual's license notice.
I. Include an unaltered copy of this License.
J. Preserve the network location, if any, given in the Manual for
public access to a Transparent copy of the Manual, and likewise
those network locations given in the Manual for any earlier
works it was based on (but you may delete those for works
that were published at least four years before the Manual itself).
This requirement may be waived for a certain network location
by the original publisher of the version it refers to.
K. In any section entitled "Acknowledgements" or "Dedications",
preserve the section's title, and preserve in the section all the
substance of each of the contributor acknowledgements and/or
dedications given therein.
L. Preserve all the Invariant Sections of the Manual,
unaltered in their text and in their titles. Section numbers
or the equivalent are not considered part of the section titles.
M. Delete any section entitled "Endorsements". Such a section
may not be included in the Modified Version.
N. Do not retitle any existing section as "Endorsements"
or to conflict in title with any Invariant Section.
If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Manual, 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 Manual 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 Manual do not by this License give permission to use their names for publicity or to assert or imply endorsement of any Modified Version.
5. COMBINING MANUALS
You may combine the Manual with other manuals released under this License, under the terms defined in section 4 above for modified versions, provided that you include all of the Invariant Sections of all of the original manuals, unmodified, in the combination, and list them all as Invariant Sections in your combined work.
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 title in the list of Invariant Sections in the license notice of the combined work.
6. AGGREGATION WITH INDEPENDENT WORKS
A compilation of the Manual or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, does not as a whole count as a Modified Version of the Manual, provided no compilation copyright is claimed for the compilation. In such a compilation, this License does not apply to the other self-contained works thus compiled with the Manual, on account of their being thus compiled, if they are not themselves derivative works of the Manual. If the Manual is less than one quarter of the entire aggregate, the Manual's Cover Texts may be placed on covers that surround only the Manual within the aggregate. Otherwise they must appear on covers around the whole aggregate.
7. TRANSLATION
Translation is considered a kind of modification, so you may distribute translations of the manual 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 provided that you also include the original English version of this License. In case of a disagreement between the translation and the original English version of this License, the original English version will prevail.
8. TERMINATION
You may not copy, modify, sublicense, or distribute the Manual except as expressly provided for under this License. Any other attempt to copy, modify, sublicense or distribute the Manual is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.
9. 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.
Each version of the License is given a distinguishing version number. If the Manual 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 by the Free Software Foundation. If the Manual does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation.
10. ADDENDUM: How to use this License for your manuals
To use this License in a manual you have written, include a copy of the License in the manual 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 manual under the terms of the GNU Free Documentation License, Version 1.0 or any later version published by the Free Software Foundation; with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. A copy of the license is included in the section entitled "GNU Free Documentation License".
If you have no Invariant Sections, write "with no Invariant Sections" instead of saying which ones are invariant. If you have no Front-Cover Texts, write "no Front-Cover Texts" instead of "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
If your manual 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.