GNU Free Documentation Licence
Copyright (C) 2000,2001,2002 Free Software Foundation, Inc. 51 Franklin
St, Fifth Floor, Boston, MA 02110-1301 USA Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
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.
1. 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
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, that is suitable for revising the document 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, or absence of markup, has been arranged to thwart or discourage
subsequent modification by readers is not Transparent. An image format is not Transparent if used for
any substantial amount of 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
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.
2. VERBATIM COPYING
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 section 3. You may
also lend copies, under the same conditions stated above, and you may publicly display copies.
3. 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
A. 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
B. 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
C. State on the Title page the name of the publisher of the Modified Version, as the publisher.
D. Preserve all the copyright notices of the 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 Modified Version under the terms of this License, in the form shown in the Addendum below.
G. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given
in the Document's license notice. H. Include an unaltered copy of this License.
I. 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.
J. 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.
K. 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.
L. 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.
M. Delete any section Entitled "Endorsements". Such a section may not be included in the Modified
N. Do not retitle any existing section to be Entitled "Endorsements" or to conflict in title
with any Invariant Section.
O. 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
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.
5. COMBINING DOCUMENTS
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 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".
6. 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 other respects.
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.
7. 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
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
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.
10. 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 http://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:
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:
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.