[[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–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.