[[licenses-gfdl]]
== Appendix A. GNU Free Documentation License

Version 1.2, November 2002

Copyright (C) 2000, 2001, 2002 Free Software Foundation, Inc.  675
Mass Ave, Cambridge, MA 02139, USA

Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.

[[licenses-gfdl-section-1]]
=== Preamble

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.

[[licenses-gfdl-section-2]]

=== 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.

anchor:modified-version[Modified Version]

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.

anchor:secondary-section[Secondary Section]

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.

anchor:invariant-sections[Invariant Sections]

The ``Invariant Sections'' are certain <<secondary-section>> 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 Section then there are none.

anchor:cover-texts[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 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.
        
anchor:transparent[Transparent]

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 only.

anchor:title-page[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.
        
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.

[[licenses-gfdl-section-3]]

=== 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
<<licenses-gfdl-section-4>>.
    
You may also lend copies, under the same conditions stated above, and
you may publicly display copies.

[[licenses-gfdl-section-4]]

=== 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.
    
[[licenses-gfdl-section-5]]

=== Modifications

You may copy and distribute a <<modified-version>> of the Document
under the conditions of sections <<licenses-gfdl-section-3>> and
<<licenses-gfdl-section-4>> 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 <<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 gives
permission.

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 requirement.

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-version>>.

n. Do not retitle any existing section to be Entitled ``Endorsements''
or to conflict in title with any <<invariant-sections>>.

o. Preserve any Warranty Disclaimers.
    
If the <<modified-version>> includes new front-matter sections or
appendices that qualify as <<secondary-section>> 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&ndash;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>>.
    
[[licenses-gfdl-section-6]]

=== Combining documents

You may combine the Document with other documents released under this
License, under the terms defined in section
<<licenses-gfdl-section-5>> 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''.
    
[[licenses-gfdl-section-7]]

=== Collection 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.
    
[[licenses-gfdl-section-8]]

=== 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 <<licenses-gfdl-section-4>>
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.
    
[[licenses-gfdl-section-9]]

=== Translations

Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section
<<licenses-gfdl-section-5>>.  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
<<licenses-gfdl-section-5>>) to Preserve its Title (section
<<licenses-gfdl-section-2>>) will typically require changing the
actual title.

[[licenses-gfdl-section-10]]

=== Termination

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.

[[licenses-gfdl-section-11]]

=== 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/[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.

[[licenses-gfdl-section-12]]

=== 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.
