1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2
3.. _fdl:
4
5******************************
6GNU Free Documentation License
7******************************
8
9
10.. _fdl-preamble:
11
120. PREAMBLE
13===========
14
15The purpose of this License is to make a manual, textbook, or other
16written document "free" in the sense of freedom: to assure everyone the
17effective freedom to copy and redistribute it, with or without modifying
18it, either commercially or noncommercially. Secondarily, this License
19preserves for the author and publisher a way to get credit for their
20work, while not being considered responsible for modifications made by
21others.
22
23This License is a kind of "copyleft", which means that derivative works
24of the document must themselves be free in the same sense. It
25complements the GNU General Public License, which is a copyleft license
26designed for free software.
27
28We have designed this License in order to use it for manuals for free
29software, because free software needs free documentation: a free program
30should come with manuals providing the same freedoms that the software
31does. But this License is not limited to software manuals; it can be
32used for any textual work, regardless of subject matter or whether it is
33published as a printed book. We recommend this License principally for
34works whose purpose is instruction or reference.
35
36
37.. _fdl-section1:
38
391. APPLICABILITY AND DEFINITIONS
40================================
41
42
43.. _fdl-document:
44
45This License applies to any manual or other work that contains a notice
46placed by the copyright holder saying it can be distributed under the
47terms of this License. The "Document", below, refers to any such manual
48or work. Any member of the public is a licensee, and is addressed as
49"you".
50
51
52.. _fdl-modified:
53
54A "Modified Version" of the Document means any work containing the
55Document or a portion of it, either copied verbatim, or with
56modifications and/or translated into another language.
57
58
59.. _fdl-secondary:
60
61A "Secondary Section" is a named appendix or a front-matter section of
62the :ref:`Document <fdl-document>` that deals exclusively with the
63relationship of the publishers or authors of the Document to the
64Document's overall subject (or to related matters) and contains nothing
65that could fall directly within that overall subject. (For example, if
66the Document is in part a textbook of mathematics, a Secondary Section
67may not explain any mathematics.) The relationship could be a matter of
68historical connection with the subject or with related matters, or of
69legal, commercial, philosophical, ethical or political position
70regarding them.
71
72
73.. _fdl-invariant:
74
75The "Invariant Sections" are certain
76:ref:`Secondary Sections <fdl-secondary>` whose titles are designated,
77as being those of Invariant Sections, in the notice that says that the
78:ref:`Document <fdl-document>` is released under this License.
79
80
81.. _fdl-cover-texts:
82
83The "Cover Texts" are certain short passages of text that are listed, as
84Front-Cover Texts or Back-Cover Texts, in the notice that says that the
85:ref:`Document <fdl-document>` is released under this License.
86
87
88.. _fdl-transparent:
89
90A "Transparent" copy of the :ref:`Document <fdl-document>` means a
91machine-readable copy, represented in a format whose specification is
92available to the general public, whose contents can be viewed and edited
93directly and straightforwardly with generic text editors or (for images
94composed of pixels) generic paint programs or (for drawings) some widely
95available drawing editor, and that is suitable for input to text
96formatters or for automatic translation to a variety of formats suitable
97for input to text formatters. A copy made in an otherwise Transparent
98file format whose markup has been designed to thwart or discourage
99subsequent modification by readers is not Transparent. A copy that is
100not "Transparent" is called "Opaque".
101
102Examples of suitable formats for Transparent copies include plain ASCII
103without markup, Texinfo input format, LaTeX input format, SGML or XML
104using a publicly available DTD, and standard-conforming simple HTML
105designed for human modification. Opaque formats include PostScript, PDF,
106proprietary formats that can be read and edited only by proprietary word
107processors, SGML or XML for which the DTD and/or processing tools are
108not generally available, and the machine-generated HTML produced by some
109word processors for output purposes only.
110
111
112.. _fdl-title-page:
113
114The "Title Page" means, for a printed book, the title page itself, plus
115such following pages as are needed to hold, legibly, the material this
116License requires to appear in the title page. For works in formats which
117do not have any title page as such, "Title Page" means the text near the
118most prominent appearance of the work's title, preceding the beginning
119of the body of the text.
120
121
122.. _fdl-section2:
123
1242. VERBATIM COPYING
125===================
126
127You may copy and distribute the :ref:`Document <fdl-document>` in any
128medium, either commercially or noncommercially, provided that this
129License, the copyright notices, and the license notice saying this
130License applies to the Document are reproduced in all copies, and that
131you add no other conditions whatsoever to those of this License. You may
132not use technical measures to obstruct or control the reading or further
133copying of the copies you make or distribute. However, you may accept
134compensation in exchange for copies. If you distribute a large enough
135number of copies you must also follow the conditions in
136:ref:`section 3 <fdl-section3>`.
137
138You may also lend copies, under the same conditions stated above, and
139you may publicly display copies.
140
141
142.. _fdl-section3:
143
1443. COPYING IN QUANTITY
145======================
146
147If you publish printed copies of the :ref:`Document <fdl-document>`
148numbering more than 100, and the Document's license notice requires
149:ref:`Cover Texts <fdl-cover-texts>`, you must enclose the copies in
150covers that carry, clearly and legibly, all these Cover Texts:
151Front-Cover Texts on the front cover, and Back-Cover Texts on the back
152cover. Both covers must also clearly and legibly identify you as the
153publisher of these copies. The front cover must present the full title
154with all words of the title equally prominent and visible. You may add
155other material on the covers in addition. Copying with changes limited
156to the covers, as long as they preserve the title of the
157:ref:`Document <fdl-document>` and satisfy these conditions, can be
158treated as verbatim copying in other respects.
159
160If the required texts for either cover are too voluminous to fit
161legibly, you should put the first ones listed (as many as fit
162reasonably) on the actual cover, and continue the rest onto adjacent
163pages.
164
165If you publish or distribute :ref:`Opaque <fdl-transparent>` copies of
166the :ref:`Document <fdl-document>` numbering more than 100, you must
167either include a machine-readable :ref:`Transparent <fdl-transparent>`
168copy along with each Opaque copy, or state in or with each Opaque copy a
169publicly-accessible computer-network location containing a complete
170Transparent copy of the Document, free of added material, which the
171general network-using public has access to download anonymously at no
172charge using public-standard network protocols. If you use the latter
173option, you must take reasonably prudent steps, when you begin
174distribution of Opaque copies in quantity, to ensure that this
175Transparent copy will remain thus accessible at the stated location
176until at least one year after the last time you distribute an Opaque
177copy (directly or through your agents or retailers) of that edition to
178the public.
179
180It is requested, but not required, that you contact the authors of the
181:ref:`Document <fdl-document>` well before redistributing any large
182number of copies, to give them a chance to provide you with an updated
183version of the Document.
184
185
186.. _fdl-section4:
187
1884. MODIFICATIONS
189================
190
191You may copy and distribute a :ref:`Modified Version <fdl-modified>`
192of the :ref:`Document <fdl-document>` under the conditions of sections
193:ref:`2 <fdl-section2>` and :ref:`3 <fdl-section3>` above, provided
194that you release the Modified Version under precisely this License, with
195the Modified Version filling the role of the Document, thus licensing
196distribution and modification of the Modified Version to whoever
197possesses a copy of it. In addition, you must do these things in the
198Modified Version:
199
200-  **A.**
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.
207
208-  **B.**
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
214   has less than five).
215
216-  **C.**
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
219   publisher.
220
221-  **D.**
222   Preserve all the copyright notices of the
223   :ref:`Document <fdl-document>`.
224
225-  **E.**
226   Add an appropriate copyright notice for your modifications adjacent
227   to the other copyright notices.
228
229-  **F.**
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.
234
235-  **G.**
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.
240
241-  **H.**
242   Include an unaltered copy of this License.
243
244-  **I.**
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.
253
254-  **J.**
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.
263
264-  **K.**
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.
269
270-  **L.**
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.
275
276-  **M.**
277   Delete any section entitled "Endorsements". Such a section may not be
278   included in the :ref:`Modified Version <fdl-modified>`.
279
280-  **N.**
281   Do not retitle any existing section as "Endorsements" or to conflict
282   in title with any :ref:`Invariant Section <fdl-invariant>`.
283
284If the :ref:`Modified Version <fdl-modified>` includes new
285front-matter sections or appendices that qualify as
286:ref:`Secondary Sections <fdl-secondary>` and contain no material
287copied from the Document, you may at your option designate some or all
288of these sections as invariant. To do this, add their titles to the list
289of :ref:`Invariant Sections <fdl-invariant>` in the Modified Version's
290license notice. These titles must be distinct from any other section
291titles.
292
293You may add a section entitled "Endorsements", provided it contains
294nothing but endorsements of your
295:ref:`Modified Version <fdl-modified>` by various parties--for
296example, statements of peer review or that the text has been approved by
297an organization as the authoritative definition of a standard.
298
299You 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
301words as a :ref:`Back-Cover Text <fdl-cover-texts>`, to the end of the
302list of :ref:`Cover Texts <fdl-cover-texts>` in the
303:ref:`Modified Version <fdl-modified>`. Only one passage of
304Front-Cover Text and one of Back-Cover Text may be added by (or through
305arrangements made by) any one entity. If the
306:ref:`Document <fdl-document>` already includes a cover text for the
307same cover, previously added by you or by arrangement made by the same
308entity you are acting on behalf of, you may not add another; but you may
309replace the old one, on explicit permission from the previous publisher
310that added the old one.
311
312The author(s) and publisher(s) of the :ref:`Document <fdl-document>`
313do not by this License give permission to use their names for publicity
314for or to assert or imply endorsement of any
315:ref:`Modified Version <fdl-modified>`.
316
317
318.. _fdl-section5:
319
3205. COMBINING DOCUMENTS
321======================
322
323You may combine the :ref:`Document <fdl-document>` with other
324documents released under this License, under the terms defined in
325:ref:`section 4 <fdl-section4>` above for modified versions, provided
326that you include in the combination all of the
327:ref:`Invariant Sections <fdl-invariant>` of all of the original
328documents, unmodified, and list them all as Invariant Sections of your
329combined work in its license notice.
330
331The combined work need only contain one copy of this License, and
332multiple identical :ref:`Invariant Sections <fdl-invariant>` may be
333replaced with a single copy. If there are multiple Invariant Sections
334with the same name but different contents, make the title of each such
335section unique by adding at the end of it, in parentheses, the name of
336the original author or publisher of that section if known, or else a
337unique number. Make the same adjustment to the section titles in the
338list of Invariant Sections in the license notice of the combined work.
339
340In the combination, you must combine any sections entitled "History" in
341the various original documents, forming one section entitled "History";
342likewise combine any sections entitled "Acknowledgements", and any
343sections entitled "Dedications". You must delete all sections entitled
344"Endorsements."
345
346
347.. _fdl-section6:
348
3496. COLLECTIONS OF DOCUMENTS
350===========================
351
352You may make a collection consisting of the
353:ref:`Document <fdl-document>` and other documents released under this
354License, and replace the individual copies of this License in the
355various documents with a single copy that is included in the collection,
356provided that you follow the rules of this License for verbatim copying
357of each of the documents in all other respects.
358
359You may extract a single document from such a collection, and distribute
360it individually under this License, provided you insert a copy of this
361License into the extracted document, and follow this License in all
362other respects regarding verbatim copying of that document.
363
364
365.. _fdl-section7:
366
3677. AGGREGATION WITH INDEPENDENT WORKS
368=====================================
369
370A compilation of the :ref:`Document <fdl-document>` or its derivatives
371with other separate and independent documents or works, in or on a
372volume of a storage or distribution medium, does not as a whole count as
373a :ref:`Modified Version <fdl-modified>` of the Document, provided no
374compilation copyright is claimed for the compilation. Such a compilation
375is called an "aggregate", and this License does not apply to the other
376self-contained works thus compiled with the Document , on account of
377their being thus compiled, if they are not themselves derivative works
378of the Document. If the :ref:`Cover Text <fdl-cover-texts>`
379requirement of :ref:`section 3 <fdl-section3>` is applicable to these
380copies of the Document, then if the Document is less than one quarter of
381the entire aggregate, the Document's Cover Texts may be placed on covers
382that surround only the Document within the aggregate. Otherwise they
383must appear on covers around the whole aggregate.
384
385
386.. _fdl-section8:
387
3888. TRANSLATION
389==============
390
391Translation is considered a kind of modification, so you may distribute
392translations 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
395special permission from their copyright holders, but you may include
396translations of some or all Invariant Sections in addition to the
397original versions of these Invariant Sections. You may include a
398translation of this License provided that you also include the original
399English version of this License. In case of a disagreement between the
400translation and the original English version of this License, the
401original English version will prevail.
402
403
404.. _fdl-section9:
405
4069. TERMINATION
407==============
408
409You may not copy, modify, sublicense, or distribute the
410:ref:`Document <fdl-document>` except as expressly provided for under
411this License. Any other attempt to copy, modify, sublicense or
412distribute the Document is void, and will automatically terminate your
413rights under this License. However, parties who have received copies, or
414rights, from you under this License will not have their licenses
415terminated so long as such parties remain in full compliance.
416
417
418.. _fdl-section10:
419
42010. FUTURE REVISIONS OF THIS LICENSE
421====================================
422
423The `Free Software Foundation <http://www.gnu.org/fsf/fsf.html>`__
424may publish new, revised versions of the GNU Free Documentation License
425from time to time. Such new versions will be similar in spirit to the
426present version, but may differ in detail to address new problems or
427concerns. See
428`http://www.gnu.org/copyleft/ <http://www.gnu.org/copyleft>`__.
429
430Each version of the License is given a distinguishing version number. If
431the :ref:`Document <fdl-document>` specifies that a particular
432numbered version of this License "or any later version" applies to it,
433you have the option of following the terms and conditions either of that
434specified version or of any later version that has been published (not
435as a draft) by the Free Software Foundation. If the Document does not
436specify a version number of this License, you may choose any version
437ever published (not as a draft) by the Free Software Foundation.
438
439
440.. _fdl-using:
441
442Addendum
443========
444
445To use this License in a document you have written, include a copy of
446the License in the document and put the following copyright and license
447notices just after the title page:
448
449    Copyright © YEAR YOUR NAME.
450
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".
460
461If you have no :ref:`Invariant Sections <fdl-invariant>`, write "with
462no Invariant Sections" instead of saying which ones are invariant. If
463you have no :ref:`Front-Cover Texts <fdl-cover-texts>`, write "no
464Front-Cover Texts" instead of "Front-Cover Texts being LIST"; likewise
465for :ref:`Back-Cover Texts <fdl-cover-texts>`.
466
467If your document contains nontrivial examples of program code, we
468recommend releasing these examples in parallel under your choice of free
469software license, such as the
470`GNU General Public License <http://www.gnu.org/copyleft/gpl.html>`__,
471to permit their use in free software.
472