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.
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,
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available drawing editor, and that is suitable for input to text formatters or for
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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
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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.
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.
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
You may also lend copies, under the same conditions stated above, and you may publicly
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.
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:
GNU FDL Modification Conditions
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
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.
State on the Title page the name of the publisher of the Modified Version,
as the publisher.
Preserve all the copyright notices of the Document.
Add an appropriate copyright notice for your modifications adjacent to the
other copyright notices.
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.
Preserve in that license notice the full lists of Invariant Sections and
required Cover Texts given in the Document's license notice.
Include an unaltered copy of this License.
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.
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.
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.
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.
Delete any section Entitled "Endorsements". Such a section may not be
included in the Modified Version.
Do not retitle any existing section to be Entitled "Endorsements" or to
conflict in title with any Invariant Section.
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.
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
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".
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
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.
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.
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.
You may not copy, modify, sublicense, or distribute the 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.
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 https://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.
ADDENDUM: How to use this License for your documents
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:
Sample Invariant Sections list
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".
If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the
"with...Texts." line with this:
Sample Invariant Sections list
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.
Appendix�A.�Creative Commons by Attribution-ShareAlike 2.0�
Published under the terms of the GNU General Public License