GNU Free Documentation License
Version 1.1, March 2000
Copyright © 2000 Free Software Foundation, Inc.
59 Temple Place, Suite 330, Boston, MA 02111-1307 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 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
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 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
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. (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.
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.
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 "Transparent" copy of the 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.
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.
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 display copies.
If you publish printed copies 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
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 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
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:
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 less than five).
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", and 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
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. 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
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 as "Endorsements" or
to conflict in title with any Invariant Section.
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.
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
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, does not as a whole count as a Modified Version 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 Cover Text requirement of section 3 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.
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 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.
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.