| .. -*- coding: utf-8; mode: rst -*- | 
 |  | 
 | .. _fdl: | 
 |  | 
 | ****************************** | 
 | GNU Free Documentation License | 
 | ****************************** | 
 |  | 
 |  | 
 | .. _fdl-preamble: | 
 |  | 
 | 0. PREAMBLE | 
 | =========== | 
 |  | 
 | The purpose of this License is to make a manual, textbook, or other | 
 | written 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. | 
 |  | 
 |  | 
 | .. _fdl-section1: | 
 |  | 
 | 1. APPLICABILITY AND DEFINITIONS | 
 | ================================ | 
 |  | 
 |  | 
 | .. _fdl-document: | 
 |  | 
 | 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 “Document”, below, refers to any such manual | 
 | or work. Any member of the public is a licensee, and is addressed as | 
 | “you”. | 
 |  | 
 |  | 
 | .. _fdl-modified: | 
 |  | 
 | 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. | 
 |  | 
 |  | 
 | .. _fdl-secondary: | 
 |  | 
 | A “Secondary Section” is a named appendix or a front-matter section of | 
 | the :ref:`Document <fdl-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. (For example, 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. | 
 |  | 
 |  | 
 | .. _fdl-invariant: | 
 |  | 
 | The “Invariant Sections” are certain | 
 | :ref:`Secondary Sections <fdl-secondary>` whose titles are designated, | 
 | as being those of Invariant Sections, in the notice that says that the | 
 | :ref:`Document <fdl-document>` is released under this License. | 
 |  | 
 |  | 
 | .. _fdl-cover-texts: | 
 |  | 
 | 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 | 
 | :ref:`Document <fdl-document>` is released under this License. | 
 |  | 
 |  | 
 | .. _fdl-transparent: | 
 |  | 
 | A “Transparent” copy of the :ref:`Document <fdl-document>` 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. | 
 |  | 
 |  | 
 | .. _fdl-title-page: | 
 |  | 
 | 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. | 
 |  | 
 |  | 
 | .. _fdl-section2: | 
 |  | 
 | 2. VERBATIM COPYING | 
 | =================== | 
 |  | 
 | You may copy and distribute the :ref:`Document <fdl-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 | 
 | :ref:`section 3 <fdl-section3>`. | 
 |  | 
 | You may also lend copies, under the same conditions stated above, and | 
 | you may publicly display copies. | 
 |  | 
 |  | 
 | .. _fdl-section3: | 
 |  | 
 | 3. COPYING IN QUANTITY | 
 | ====================== | 
 |  | 
 | If you publish printed copies of the :ref:`Document <fdl-document>` | 
 | numbering more than 100, and the Document's license notice requires | 
 | :ref:`Cover Texts <fdl-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 | 
 | :ref:`Document <fdl-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 :ref:`Opaque <fdl-transparent>` copies of | 
 | the :ref:`Document <fdl-document>` numbering more than 100, you must | 
 | either include a machine-readable :ref:`Transparent <fdl-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 Document, 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 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 | 
 | :ref:`Document <fdl-document>` well before redistributing any large | 
 | number of copies, to give them a chance to provide you with an updated | 
 | version of the Document. | 
 |  | 
 |  | 
 | .. _fdl-section4: | 
 |  | 
 | 4. MODIFICATIONS | 
 | ================ | 
 |  | 
 | You may copy and distribute a :ref:`Modified Version <fdl-modified>` | 
 | of the :ref:`Document <fdl-document>` under the conditions of sections | 
 | :ref:`2 <fdl-section2>` and :ref:`3 <fdl-section3>` 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: | 
 |  | 
 | -  **A.** | 
 |    Use in the :ref:`Title Page <fdl-title-page>` (and on the covers, | 
 |    if any) a title distinct from that of the | 
 |    :ref:`Document <fdl-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. | 
 |  | 
 | -  **B.** | 
 |    List on the :ref:`Title Page <fdl-title-page>`, as authors, one or | 
 |    more persons or entities responsible for authorship of the | 
 |    modifications in the :ref:`Modified Version <fdl-modified>`, | 
 |    together with at least five of the principal authors of the | 
 |    :ref:`Document <fdl-document>` (all of its principal authors, if it | 
 |    has less than five). | 
 |  | 
 | -  **C.** | 
 |    State on the :ref:`Title Page <fdl-title-page>` the name of the | 
 |    publisher of the :ref:`Modified Version <fdl-modified>`, as the | 
 |    publisher. | 
 |  | 
 | -  **D.** | 
 |    Preserve all the copyright notices of the | 
 |    :ref:`Document <fdl-document>`. | 
 |  | 
 | -  **E.** | 
 |    Add an appropriate copyright notice for your modifications adjacent | 
 |    to the other copyright notices. | 
 |  | 
 | -  **F.** | 
 |    Include, immediately after the copyright notices, a license notice | 
 |    giving the public permission to use the | 
 |    :ref:`Modified Version <fdl-modified>` under the terms of this | 
 |    License, in the form shown in the Addendum below. | 
 |  | 
 | -  **G.** | 
 |    Preserve in that license notice the full lists of | 
 |    :ref:`Invariant Sections <fdl-invariant>` and required | 
 |    :ref:`Cover Texts <fdl-cover-texts>` given in the | 
 |    :ref:`Document's <fdl-document>` license notice. | 
 |  | 
 | -  **H.** | 
 |    Include an unaltered copy of this License. | 
 |  | 
 | -  **I.** | 
 |    Preserve the section entitled “History”, and its title, and add to it | 
 |    an item stating at least the title, year, new authors, and publisher | 
 |    of the :ref:`Modified Version <fdl-modified>` as given on the | 
 |    :ref:`Title Page <fdl-title-page>`. If there is no section entitled | 
 |    “History” in the :ref:`Document <fdl-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. | 
 |  | 
 | -  **J.** | 
 |    Preserve the network location, if any, given in the | 
 |    :ref:`Document <fdl-document>` for public access to a | 
 |    :ref:`Transparent <fdl-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. | 
 |  | 
 | -  **K.** | 
 |    In any section entitled “Acknowledgements” or “Dedications”, preserve | 
 |    the section's title, and preserve in the section all the substance | 
 |    and tone of each of the contributor acknowledgements and/or | 
 |    dedications given therein. | 
 |  | 
 | -  **L.** | 
 |    Preserve all the :ref:`Invariant Sections <fdl-invariant>` of the | 
 |    :ref:`Document <fdl-document>`, 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 :ref:`Modified Version <fdl-modified>`. | 
 |  | 
 | -  **N.** | 
 |    Do not retitle any existing section as “Endorsements” or to conflict | 
 |    in title with any :ref:`Invariant Section <fdl-invariant>`. | 
 |  | 
 | If the :ref:`Modified Version <fdl-modified>` includes new | 
 | front-matter sections or appendices that qualify as | 
 | :ref:`Secondary Sections <fdl-secondary>` 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 :ref:`Invariant Sections <fdl-invariant>` 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 | 
 | :ref:`Modified Version <fdl-modified>` 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 | 
 | :ref:`Front-Cover Text <fdl-cover-texts>`, and a passage of up to 25 | 
 | words as a :ref:`Back-Cover Text <fdl-cover-texts>`, to the end of the | 
 | list of :ref:`Cover Texts <fdl-cover-texts>` in the | 
 | :ref:`Modified Version <fdl-modified>`. 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 | 
 | :ref:`Document <fdl-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 :ref:`Document <fdl-document>` | 
 | do not by this License give permission to use their names for publicity | 
 | for or to assert or imply endorsement of any | 
 | :ref:`Modified Version <fdl-modified>`. | 
 |  | 
 |  | 
 | .. _fdl-section5: | 
 |  | 
 | 5. COMBINING DOCUMENTS | 
 | ====================== | 
 |  | 
 | You may combine the :ref:`Document <fdl-document>` with other | 
 | documents released under this License, under the terms defined in | 
 | :ref:`section 4 <fdl-section4>` above for modified versions, provided | 
 | that you include in the combination all of the | 
 | :ref:`Invariant Sections <fdl-invariant>` of all of the original | 
 | documents, unmodified, and list them all as Invariant Sections of your | 
 | combined work in its license notice. | 
 |  | 
 | The combined work need only contain one copy of this License, and | 
 | multiple identical :ref:`Invariant Sections <fdl-invariant>` 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.” | 
 |  | 
 |  | 
 | .. _fdl-section6: | 
 |  | 
 | 6. COLLECTIONS OF DOCUMENTS | 
 | =========================== | 
 |  | 
 | You may make a collection consisting of the | 
 | :ref:`Document <fdl-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 dispbibute | 
 | 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. | 
 |  | 
 |  | 
 | .. _fdl-section7: | 
 |  | 
 | 7. AGGREGATION WITH INDEPENDENT WORKS | 
 | ===================================== | 
 |  | 
 | A compilation of the :ref:`Document <fdl-document>` 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 :ref:`Modified Version <fdl-modified>` of the Document, provided no | 
 | compilation copyright is claimed for the compilation. Such a compilation | 
 | is called an “aggregate”, and this License does not apply to the other | 
 | self-contained works thus compiled with the Document , on account of | 
 | their being thus compiled, if they are not themselves derivative works | 
 | of the Document. If the :ref:`Cover Text <fdl-cover-texts>` | 
 | requirement of :ref:`section 3 <fdl-section3>` is applicable to these | 
 | copies of the Document, then if the Document is less than one quarter of | 
 | the entire aggregate, the Document's Cover Texts may be placed on covers | 
 | that surround only the Document within the aggregate. Otherwise they | 
 | must appear on covers around the whole aggregate. | 
 |  | 
 |  | 
 | .. _fdl-section8: | 
 |  | 
 | 8. TRANSLATION | 
 | ============== | 
 |  | 
 | Translation is considered a kind of modification, so you may distribute | 
 | translations of the :ref:`Document <fdl-document>` under the terms of | 
 | :ref:`section 4 <fdl-section4>`. Replacing | 
 | :ref:`Invariant Sections <fdl-invariant>` 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. | 
 |  | 
 |  | 
 | .. _fdl-section9: | 
 |  | 
 | 9. TERMINATION | 
 | ============== | 
 |  | 
 | You may not copy, modify, sublicense, or distribute the | 
 | :ref:`Document <fdl-document>` except as expressly provided for under | 
 | this License. Any other attempt to copy, modify, sublicense or | 
 | distribute the Document 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. | 
 |  | 
 |  | 
 | .. _fdl-section10: | 
 |  | 
 | 10. FUTURE REVISIONS OF THIS LICENSE | 
 | ==================================== | 
 |  | 
 | The `Free Software Foundation <http://www.gnu.org/fsf/fsf.html>`__ | 
 | 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/ <http://www.gnu.org/copyleft>`__. | 
 |  | 
 | Each version of the License is given a distinguishing version number. If | 
 | the :ref:`Document <fdl-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. | 
 |  | 
 |  | 
 | .. _fdl-using: | 
 |  | 
 | Addendum | 
 | ======== | 
 |  | 
 | 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 © YEAR YOUR NAME. | 
 |  | 
 |     Permission is granted to copy, distribute and/or modify this | 
 |     document under the terms of the GNU Free Documentation License, | 
 |     Version 1.1 or any later version published by the Free Software | 
 |     Foundation; with the :ref:`Invariant Sections <fdl-invariant>` | 
 |     being LIST THEIR TITLES, with the | 
 |     :ref:`Front-Cover Texts <fdl-cover-texts>` being LIST, and with | 
 |     the :ref:`Back-Cover Texts <fdl-cover-texts>` being LIST. A copy | 
 |     of the license is included in the section entitled “GNU Free | 
 |     Documentation License”. | 
 |  | 
 | If you have no :ref:`Invariant Sections <fdl-invariant>`, write “with | 
 | no Invariant Sections” instead of saying which ones are invariant. If | 
 | you have no :ref:`Front-Cover Texts <fdl-cover-texts>`, write “no | 
 | Front-Cover Texts” instead of “Front-Cover Texts being LIST”; likewise | 
 | for :ref:`Back-Cover Texts <fdl-cover-texts>`. | 
 |  | 
 | 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 <http://www.gnu.org/copyleft/gpl.html>`__, | 
 | to permit their use in free software. |