1 .. -*- coding: utf-8; mode: rst -*-
5 ******************************
6 GNU Free Documentation License
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15 The purpose of this License is to make a manual, textbook, or other
16 written document “free” in the sense of freedom: to assure everyone the
17 effective freedom to copy and redistribute it, with or without modifying
18 it, either commercially or noncommercially. Secondarily, this License
19 preserves for the author and publisher a way to get credit for their
20 work, while not being considered responsible for modifications made by
23 This License is a kind of “copyleft”, which means that derivative works
24 of the document must themselves be free in the same sense. It
25 complements the GNU General Public License, which is a copyleft license
26 designed for free software.
28 We have designed this License in order to use it for manuals for free
29 software, because free software needs free documentation: a free program
30 should come with manuals providing the same freedoms that the software
31 does. But this License is not limited to software manuals; it can be
32 used for any textual work, regardless of subject matter or whether it is
33 published as a printed book. We recommend this License principally for
34 works whose purpose is instruction or reference.
39 1. APPLICABILITY AND DEFINITIONS
40 ================================
45 This License applies to any manual or other work that contains a notice
46 placed by the copyright holder saying it can be distributed under the
47 terms of this License. The “Document”, below, refers to any such manual
48 or work. Any member of the public is a licensee, and is addressed as
54 A “Modified Version” of the Document means any work containing the
55 Document or a portion of it, either copied verbatim, or with
56 modifications and/or translated into another language.
61 A “Secondary Section” is a named appendix or a front-matter section of
62 the :ref:`Document <fdl-document>` that deals exclusively with the
63 relationship of the publishers or authors of the Document to the
64 Document's overall subject (or to related matters) and contains nothing
65 that could fall directly within that overall subject. (For example, if
66 the Document is in part a textbook of mathematics, a Secondary Section
67 may not explain any mathematics.) The relationship could be a matter of
68 historical connection with the subject or with related matters, or of
69 legal, commercial, philosophical, ethical or political position
75 The “Invariant Sections” are certain
76 :ref:`Secondary Sections <fdl-secondary>` whose titles are designated,
77 as being those of Invariant Sections, in the notice that says that the
78 :ref:`Document <fdl-document>` is released under this License.
83 The “Cover Texts” are certain short passages of text that are listed, as
84 Front-Cover Texts or Back-Cover Texts, in the notice that says that the
85 :ref:`Document <fdl-document>` is released under this License.
90 A “Transparent” copy of the :ref:`Document <fdl-document>` means a
91 machine-readable copy, represented in a format whose specification is
92 available to the general public, whose contents can be viewed and edited
93 directly and straightforwardly with generic text editors or (for images
94 composed of pixels) generic paint programs or (for drawings) some widely
95 available drawing editor, and that is suitable for input to text
96 formatters or for automatic translation to a variety of formats suitable
97 for input to text formatters. A copy made in an otherwise Transparent
98 file format whose markup has been designed to thwart or discourage
99 subsequent modification by readers is not Transparent. A copy that is
100 not “Transparent” is called “Opaque”.
102 Examples of suitable formats for Transparent copies include plain ASCII
103 without markup, Texinfo input format, LaTeX input format, SGML or XML
104 using a publicly available DTD, and standard-conforming simple HTML
105 designed for human modification. Opaque formats include PostScript, PDF,
106 proprietary formats that can be read and edited only by proprietary word
107 processors, SGML or XML for which the DTD and/or processing tools are
108 not generally available, and the machine-generated HTML produced by some
109 word processors for output purposes only.
114 The “Title Page” means, for a printed book, the title page itself, plus
115 such following pages as are needed to hold, legibly, the material this
116 License requires to appear in the title page. For works in formats which
117 do not have any title page as such, “Title Page” means the text near the
118 most prominent appearance of the work's title, preceding the beginning
119 of the body of the text.
127 You may copy and distribute the :ref:`Document <fdl-document>` in any
128 medium, either commercially or noncommercially, provided that this
129 License, the copyright notices, and the license notice saying this
130 License applies to the Document are reproduced in all copies, and that
131 you add no other conditions whatsoever to those of this License. You may
132 not use technical measures to obstruct or control the reading or further
133 copying of the copies you make or distribute. However, you may accept
134 compensation in exchange for copies. If you distribute a large enough
135 number of copies you must also follow the conditions in
136 :ref:`section 3 <fdl-section3>`.
138 You may also lend copies, under the same conditions stated above, and
139 you may publicly display copies.
144 3. COPYING IN QUANTITY
145 ======================
147 If you publish printed copies of the :ref:`Document <fdl-document>`
148 numbering more than 100, and the Document's license notice requires
149 :ref:`Cover Texts <fdl-cover-texts>`, you must enclose the copies in
150 covers that carry, clearly and legibly, all these Cover Texts:
151 Front-Cover Texts on the front cover, and Back-Cover Texts on the back
152 cover. Both covers must also clearly and legibly identify you as the
153 publisher of these copies. The front cover must present the full title
154 with all words of the title equally prominent and visible. You may add
155 other material on the covers in addition. Copying with changes limited
156 to the covers, as long as they preserve the title of the
157 :ref:`Document <fdl-document>` and satisfy these conditions, can be
158 treated as verbatim copying in other respects.
160 If the required texts for either cover are too voluminous to fit
161 legibly, you should put the first ones listed (as many as fit
162 reasonably) on the actual cover, and continue the rest onto adjacent
165 If you publish or distribute :ref:`Opaque <fdl-transparent>` copies of
166 the :ref:`Document <fdl-document>` numbering more than 100, you must
167 either include a machine-readable :ref:`Transparent <fdl-transparent>`
168 copy along with each Opaque copy, or state in or with each Opaque copy a
169 publicly-accessible computer-network location containing a complete
170 Transparent copy of the Document, free of added material, which the
171 general network-using public has access to download anonymously at no
172 charge using public-standard network protocols. If you use the latter
173 option, you must take reasonably prudent steps, when you begin
174 distribution of Opaque copies in quantity, to ensure that this
175 Transparent copy will remain thus accessible at the stated location
176 until at least one year after the last time you distribute an Opaque
177 copy (directly or through your agents or retailers) of that edition to
180 It is requested, but not required, that you contact the authors of the
181 :ref:`Document <fdl-document>` well before redistributing any large
182 number of copies, to give them a chance to provide you with an updated
183 version of the Document.
191 You may copy and distribute a :ref:`Modified Version <fdl-modified>`
192 of the :ref:`Document <fdl-document>` under the conditions of sections
193 :ref:`2 <fdl-section2>` and :ref:`3 <fdl-section3>` above, provided
194 that you release the Modified Version under precisely this License, with
195 the Modified Version filling the role of the Document, thus licensing
196 distribution and modification of the Modified Version to whoever
197 possesses a copy of it. In addition, you must do these things in the
201 Use in the :ref:`Title Page <fdl-title-page>` (and on the covers,
202 if any) a title distinct from that of the
203 :ref:`Document <fdl-document>`, and from those of previous versions
204 (which should, if there were any, be listed in the History section of
205 the Document). You may use the same title as a previous version if
206 the original publisher of that version gives permission.
209 List on the :ref:`Title Page <fdl-title-page>`, as authors, one or
210 more persons or entities responsible for authorship of the
211 modifications in the :ref:`Modified Version <fdl-modified>`,
212 together with at least five of the principal authors of the
213 :ref:`Document <fdl-document>` (all of its principal authors, if it
217 State on the :ref:`Title Page <fdl-title-page>` the name of the
218 publisher of the :ref:`Modified Version <fdl-modified>`, as the
222 Preserve all the copyright notices of the
223 :ref:`Document <fdl-document>`.
226 Add an appropriate copyright notice for your modifications adjacent
227 to the other copyright notices.
230 Include, immediately after the copyright notices, a license notice
231 giving the public permission to use the
232 :ref:`Modified Version <fdl-modified>` under the terms of this
233 License, in the form shown in the Addendum below.
236 Preserve in that license notice the full lists of
237 :ref:`Invariant Sections <fdl-invariant>` and required
238 :ref:`Cover Texts <fdl-cover-texts>` given in the
239 :ref:`Document's <fdl-document>` license notice.
242 Include an unaltered copy of this License.
245 Preserve the section entitled “History”, and its title, and add to it
246 an item stating at least the title, year, new authors, and publisher
247 of the :ref:`Modified Version <fdl-modified>` as given on the
248 :ref:`Title Page <fdl-title-page>`. If there is no section entitled
249 “History” in the :ref:`Document <fdl-document>`, create one stating
250 the title, year, authors, and publisher of the Document as given on
251 its Title Page, then add an item describing the Modified Version as
252 stated in the previous sentence.
255 Preserve the network location, if any, given in the
256 :ref:`Document <fdl-document>` for public access to a
257 :ref:`Transparent <fdl-transparent>` copy of the Document, and
258 likewise the network locations given in the Document for previous
259 versions it was based on. These may be placed in the “History”
260 section. You may omit a network location for a work that was
261 published at least four years before the Document itself, or if the
262 original publisher of the version it refers to gives permission.
265 In any section entitled “Acknowledgements” or “Dedications”, preserve
266 the section's title, and preserve in the section all the substance
267 and tone of each of the contributor acknowledgements and/or
268 dedications given therein.
271 Preserve all the :ref:`Invariant Sections <fdl-invariant>` of the
272 :ref:`Document <fdl-document>`, unaltered in their text and in
273 their titles. Section numbers or the equivalent are not considered
274 part of the section titles.
277 Delete any section entitled “Endorsements”. Such a section may not be
278 included in the :ref:`Modified Version <fdl-modified>`.
281 Do not retitle any existing section as “Endorsements” or to conflict
282 in title with any :ref:`Invariant Section <fdl-invariant>`.
284 If the :ref:`Modified Version <fdl-modified>` includes new
285 front-matter sections or appendices that qualify as
286 :ref:`Secondary Sections <fdl-secondary>` and contain no material
287 copied from the Document, you may at your option designate some or all
288 of these sections as invariant. To do this, add their titles to the list
289 of :ref:`Invariant Sections <fdl-invariant>` in the Modified Version's
290 license notice. These titles must be distinct from any other section
293 You may add a section entitled “Endorsements”, provided it contains
294 nothing but endorsements of your
295 :ref:`Modified Version <fdl-modified>` by various parties--for
296 example, statements of peer review or that the text has been approved by
297 an organization as the authoritative definition of a standard.
299 You may add a passage of up to five words as a
300 :ref:`Front-Cover Text <fdl-cover-texts>`, and a passage of up to 25
301 words as a :ref:`Back-Cover Text <fdl-cover-texts>`, to the end of the
302 list of :ref:`Cover Texts <fdl-cover-texts>` in the
303 :ref:`Modified Version <fdl-modified>`. Only one passage of
304 Front-Cover Text and one of Back-Cover Text may be added by (or through
305 arrangements made by) any one entity. If the
306 :ref:`Document <fdl-document>` already includes a cover text for the
307 same cover, previously added by you or by arrangement made by the same
308 entity you are acting on behalf of, you may not add another; but you may
309 replace the old one, on explicit permission from the previous publisher
310 that added the old one.
312 The author(s) and publisher(s) of the :ref:`Document <fdl-document>`
313 do not by this License give permission to use their names for publicity
314 for or to assert or imply endorsement of any
315 :ref:`Modified Version <fdl-modified>`.
320 5. COMBINING DOCUMENTS
321 ======================
323 You may combine the :ref:`Document <fdl-document>` with other
324 documents released under this License, under the terms defined in
325 :ref:`section 4 <fdl-section4>` above for modified versions, provided
326 that you include in the combination all of the
327 :ref:`Invariant Sections <fdl-invariant>` of all of the original
328 documents, unmodified, and list them all as Invariant Sections of your
329 combined work in its license notice.
331 The combined work need only contain one copy of this License, and
332 multiple identical :ref:`Invariant Sections <fdl-invariant>` may be
333 replaced with a single copy. If there are multiple Invariant Sections
334 with the same name but different contents, make the title of each such
335 section unique by adding at the end of it, in parentheses, the name of
336 the original author or publisher of that section if known, or else a
337 unique number. Make the same adjustment to the section titles in the
338 list of Invariant Sections in the license notice of the combined work.
340 In the combination, you must combine any sections entitled “History” in
341 the various original documents, forming one section entitled “History”;
342 likewise combine any sections entitled “Acknowledgements”, and any
343 sections entitled “Dedications”. You must delete all sections entitled
349 6. COLLECTIONS OF DOCUMENTS
350 ===========================
352 You may make a collection consisting of the
353 :ref:`Document <fdl-document>` and other documents released under this
354 License, and replace the individual copies of this License in the
355 various documents with a single copy that is included in the collection,
356 provided that you follow the rules of this License for verbatim copying
357 of each of the documents in all other respects.
359 You may extract a single document from such a collection, and dispbibute
360 it individually under this License, provided you insert a copy of this
361 License into the extracted document, and follow this License in all
362 other respects regarding verbatim copying of that document.
367 7. AGGREGATION WITH INDEPENDENT WORKS
368 =====================================
370 A compilation of the :ref:`Document <fdl-document>` or its derivatives
371 with other separate and independent documents or works, in or on a
372 volume of a storage or distribution medium, does not as a whole count as
373 a :ref:`Modified Version <fdl-modified>` of the Document, provided no
374 compilation copyright is claimed for the compilation. Such a compilation
375 is called an “aggregate”, and this License does not apply to the other
376 self-contained works thus compiled with the Document , on account of
377 their being thus compiled, if they are not themselves derivative works
378 of the Document. If the :ref:`Cover Text <fdl-cover-texts>`
379 requirement of :ref:`section 3 <fdl-section3>` is applicable to these
380 copies of the Document, then if the Document is less than one quarter of
381 the entire aggregate, the Document's Cover Texts may be placed on covers
382 that surround only the Document within the aggregate. Otherwise they
383 must appear on covers around the whole aggregate.
391 Translation is considered a kind of modification, so you may distribute
392 translations of the :ref:`Document <fdl-document>` under the terms of
393 :ref:`section 4 <fdl-section4>`. Replacing
394 :ref:`Invariant Sections <fdl-invariant>` with translations requires
395 special permission from their copyright holders, but you may include
396 translations of some or all Invariant Sections in addition to the
397 original versions of these Invariant Sections. You may include a
398 translation of this License provided that you also include the original
399 English version of this License. In case of a disagreement between the
400 translation and the original English version of this License, the
401 original English version will prevail.
409 You may not copy, modify, sublicense, or distribute the
410 :ref:`Document <fdl-document>` except as expressly provided for under
411 this License. Any other attempt to copy, modify, sublicense or
412 distribute the Document is void, and will automatically terminate your
413 rights under this License. However, parties who have received copies, or
414 rights, from you under this License will not have their licenses
415 terminated so long as such parties remain in full compliance.
420 10. FUTURE REVISIONS OF THIS LICENSE
421 ====================================
423 The `Free Software Foundation <http://www.gnu.org/fsf/fsf.html>`__
424 may publish new, revised versions of the GNU Free Documentation License
425 from time to time. Such new versions will be similar in spirit to the
426 present version, but may differ in detail to address new problems or
428 `http://www.gnu.org/copyleft/ <http://www.gnu.org/copyleft>`__.
430 Each version of the License is given a distinguishing version number. If
431 the :ref:`Document <fdl-document>` specifies that a particular
432 numbered version of this License “or any later version” applies to it,
433 you have the option of following the terms and conditions either of that
434 specified version or of any later version that has been published (not
435 as a draft) by the Free Software Foundation. If the Document does not
436 specify a version number of this License, you may choose any version
437 ever published (not as a draft) by the Free Software Foundation.
445 To use this License in a document you have written, include a copy of
446 the License in the document and put the following copyright and license
447 notices just after the title page:
449 Copyright © YEAR YOUR NAME.
451 Permission is granted to copy, distribute and/or modify this
452 document under the terms of the GNU Free Documentation License,
453 Version 1.1 or any later version published by the Free Software
454 Foundation; with the :ref:`Invariant Sections <fdl-invariant>`
455 being LIST THEIR TITLES, with the
456 :ref:`Front-Cover Texts <fdl-cover-texts>` being LIST, and with
457 the :ref:`Back-Cover Texts <fdl-cover-texts>` being LIST. A copy
458 of the license is included in the section entitled “GNU Free
459 Documentation License”.
461 If you have no :ref:`Invariant Sections <fdl-invariant>`, write “with
462 no Invariant Sections” instead of saying which ones are invariant. If
463 you have no :ref:`Front-Cover Texts <fdl-cover-texts>`, write “no
464 Front-Cover Texts” instead of “Front-Cover Texts being LIST”; likewise
465 for :ref:`Back-Cover Texts <fdl-cover-texts>`.
467 If your document contains nontrivial examples of program code, we
468 recommend releasing these examples in parallel under your choice of free
469 software license, such as the
470 `GNU General Public License <http://www.gnu.org/copyleft/gpl.html>`__,
471 to permit their use in free software.