fix documentation + add info manual

Signed-off-by: Mattias Andrée <maandree@operamail.com>

2 files changed, 933 insertions, 0 deletions

diff --git a/doc/info/bus.texinfo b/doc/info/bus.texinfo
new file mode 100644
index 0000000..ab3c276
--- /dev/null
+++ b/doc/info/bus.texinfo
@@ -0,0 +1,428 @@
+\input texinfo   @c -*-texinfo-*-
+
+@c %**start of header
+@setfilename bus.info
+@settitle bus
+@afourpaper
+@documentencoding UTF-8
+@documentlanguage en
+@finalout
+@c %**end of header
+
+
+@dircategory Interprorcess Communication
+@direntry
+* bus: (bus).                        A simple daemonless system for broadcasting messages locally
+@end direntry
+
+
+@copying
+Copyright @copyright{} 2015 Mattias Andrée
+
+@quotation
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.3 or
+any later version published by the Free Software Foundation; with no
+Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+Texts. A copy of the license is included in the section entitled
+``GNU Free Documentation License''.
+@end quotation
+@end copying
+
+@ifnottex
+@node Top
+@top bus -- A simple daemonless system for broadcasting messages locally
+@insertcopying
+@end ifnottex
+
+@titlepage
+@title bus
+@subtitle A simple daemonless system for broadcasting messages locally
+@author by Mattias Andrée (maandree)
+
+@page
+@vskip 0pt plus 1filll
+@insertcopying
+@page
+@end titlepage
+
+@contents
+
+
+@iftex
+@macro xrm{}
+@rm{}
+@end macro
+@macro xtt{}
+@tt{}
+@end macro
+@end iftex
+
+@ifnottex
+@macro xrm{}
+@end macro
+@macro xtt{}
+@end macro
+@end ifnottex
+
+
+
+@menu
+* Overview::                        Brief overview of @command{bus}.
+* Standard::                        How to use @command{bus} properly.
+* Invoking::                        Executing @command{bus}.
+* Protocol::                        How communication over @command{bus} works internally.
+* Rationale::                       Why @command{bus}?
+* GNU Free Documentation License::  Copying and sharing this manual.
+@end menu
+@c TODO @detailmenu (`C-c C-u m`)
+
+
+
+@node Overview
+@chapter Overview
+
+@command{bus} is a stupid-simple, thrilless, daemonless interprocess
+communication system for broadcasting messages. It is a lightweight
+alternative to a two-phase interprocess flexible barrier.
+
+@command{bus} uses a System V semaphore array and System V shared
+memory. Buses are named; the key of the semaphore array and the
+shared memory is stored in a regular file.
+
+The shared memory used by @command{bus} is always 2048 bytes.
+Additionally all messages should be encoded in UTF-8 and not contain
+any NULL characters, except they @emph{must} always end with a NULL
+byte. Furthermore messages should be prefixed with the process
+identifer of the process whence the message originated, followed
+by a space. If the process is ephemeral@footnote{The process exits
+after the broadcast, or shortly thereafter.}, 0 should be used
+instead of the process identifier.
+
+Communication over @command{bus} is synchronous. The broadcast call
+does not return until all listeners have received (and copied) the
+message. A malfunctioning program can lock the bus.
+
+This software package contains a C library and a command line
+utility. The package python-bus provides a Python 3 module.
+
+
+
+@node Standard
+@chapter Standard
+
+The command @command{bus create} can be used to create new buses. By
+convention, buses should be stored in @file{$XDG_RUNTIME_DIR/bus},
+this is what @command{bus create} does if no pathname is given. The
+pathname of the bus should be tracked using @env{BUS_X}, where @env{X}
+is replaced with either:
+
+@table @env
+@item GENERIC
+For the bus used in generic cases. That is all but the cases
+of the buses listed below.
+@item AUDIO
+For the bus used in with the audio subsystem is involved.
+@item VIDEO
+For the bus used in with the video subsystem is involved.
+@item INPUT
+For the bus used in with the input subsystem is involved.
+@item FILES
+For the bus used in with the storage subsystem is involved.
+@end table
+
+This list may be extended in the future. Therefore, and for
+other conventions, project-private buses should be tracked
+using @env{X_BUS}, where @env{X} is the project name.
+
+Messages broadcasted on a bus cannot be longer than 2047 bytes,
+excluding NUL termination. Message should be encoded in UTF-8,
+and most not contain the NUL character.
+
+Broadcasted message should start with the process ID whence
+the message originated, followed by a single regular space.
+If the process is ephemeral@footnote{The process exits after
+the broadcast, or shortly thereafter.}, 0 should be used instead
+of the process identifier.
+
+
+
+@node Invoking
+@chapter Invoking
+
+@command{bus} includes the following commands:
+
+@table @command
+@item create
+Create a bus.
+See @ref{bus create} for more information.
+@item remove
+Remove a bus.
+See @ref{bus remove} for more information.
+@item listen
+Listen for new message on a bus.
+See @ref{bus listen} for more information.
+@item wait
+Listen for one new message only on a bus.
+See @ref{bus wait} for more information.
+@item broadcast
+Broadcast a message on a bus.
+See @ref{bus broadcast} for more information.
+@item chmod
+Change permissions on a bus.
+See @ref{bus chmod} for more information.
+@item chown
+Change ownership of a bus.
+See @ref{bus chown} for more information.
+@item chgrp
+Change group ownership of a bus.
+See @ref{bus chgrp} for more information.
+@end table
+
+Upon successful completion, these commands exit with the value
+0. On failure, they exit with the value 1. If the command is
+not recognised the exit value is 2.
+
+@menu
+* bus create::                      Create a bus.
+* bus remove::                      Remove a bus.
+* bus listen::                      Listen for new message on a bus.
+* bus wait::                        Listen for one new message only on a bus.
+* bus broadcast::                   Broadcast a message on a bus.
+* bus chmod::                       Change permissions on a bus.
+* bus chown::                       Change ownership of a bus.
+* bus chgrp::                       Change group ownership of a bus.
+@end menu
+
+
+
+@node bus create
+@section @command{bus create}
+
+The syntax for invocation of @command{bus create} is
+@example
+bus create [-x] [--] [@var{PATHNAME}]
+@end example
+
+The command creates a bus and stores the key to it in the
+file @var{PATHNAME}. If @var{PATHNAME} is omitted, a
+random pathname in @file{$XDG_RUNTIME_DIR/bus} will be
+used and printed to stdout.
+
+If @option{-x} is used, the command will fail if
+the file @var{PATHNAME} already exists.
+
+
+
+
+@node bus remove
+@section @command{bus remove}
+
+The syntax for invocation of @command{bus remove} is
+@example
+bus remove [--] @var{PATHNAME}
+@end example
+
+The command removes the bus whose key is stored in
+the file @var{PATHNAME}.  The file holding the
+key is also unlinked.
+
+
+
+@node bus listen
+@section @command{bus listen}
+
+The syntax for invocation of @command{bus command} is
+@example
+bus listen [--] @var{PATHNAME} @var{COMMAND}
+@end example
+
+The command listens for new messages on the bus whose
+key is stored in the file @var{PATHNAME}. Once a message
+is received, @var{COMMAND} will be spawned with the
+environment variable @env{msg} (lowercased) set to the
+received message. @sc{POSIX} shell syntax applies to
+@var{COMMAND}.
+
+
+@node bus wait
+@section @command{bus wait}
+
+The syntax for invocation of @command{bus wait} is
+@example
+bus wait [--] @var{PATHNAME} @var{COMMAND}
+@end example
+
+The command listens for a new message on the bus whose
+key is stored in the file @var{PATHNAME}. Once a message
+is received, the process will stop listening for more
+messages and @var{COMMAND} will be spawned with the
+environment variable @env{msg} (lowercased) set to the
+received message. @sc{POSIX} shell syntax applies to
+@var{COMMAND}.
+
+
+
+@node bus broadcast
+@section @command{bus broadcast}
+
+The syntax for invocation of @command{bus broadcast} is
+@example
+bus broadcast [-n] [--] @var{PATHNAME} @var{MESSAGE}
+@end example
+
+The command broadcasts the message @var{MESSAGE} on the
+bus whose key is stored in the file @var{PATHNAME}.
+
+
+
+@node bus chmod
+@section @command{bus chmod}
+
+The syntax for invocation of @command{bus chmod} is
+@example
+bus chmod [--] @var{PERMISSIONS} @var{PATHNAME}
+@end example
+
+This command changes who have access to the bus whose key
+is stored in the file @var{PATHNAME}. In the permissions,
+the owner, the group, and others (not in tgroup) are
+represented by the symbols @code{u}@footnote{@code{u}
+stands for `user'.}, @code{g}, and @code{o}, respectively.
+The permissions string is imagined to have always be
+prefixed with an @code{=}. This symbols means that all user
+classes list after it, and only those classes, as permission
+to use the bus. Similarly the symbols @code{+} and @code{-}
+can be used to grant and revoke access, respectively. The
+symbols @code{=}, @code{+}, and @code{-} can be mixed, and
+are interpreted from left to right. Alternatively the
+permissions string can be a octal number, where the  owner
+is represented by any bit in 700 (100, 200, or 400, or any
+combination thereof), the group is represented by any bit
+in 70, and others (not in the group) is represented by any
+bit in 7.
+
+The current permission of the bus can be retrieved by
+running @command{stat} over the file @var{PATHNAME}.
+
+
+
+@node bus chown
+@section @command{bus chown}
+
+The syntax for invocation of @command{bus chown} is
+@example
+bus chown [--] @var{OWNER}[:@var{GROUP}] @var{PATHNAME}
+@end example
+
+This command changes the owner, that owns the bus whose
+key is stored in the file @var{PATHNAME}, to the specified
+owner. The owner can be specified either with a numerical
+user identifier or with a user name. If a group is
+specified, the bus's owner-group will be set to that group,
+otherwise the group will remain unchanged (not changed
+to the group of the new owner.) The group can be specified
+either with a numerical group identifier or with a group
+name.
+
+The current ownership of the bus can be retrieved by
+running @command{stat} over the file @var{PATHNAME}.
+
+
+
+@node bus chgrp
+@section @command{bus chgrp}
+
+The syntax for invocation of @command{bus chgrp} is
+@example
+bus chgrp [--] @var{GROUP} @var{PATHNAME}
+@end example
+
+This command changes the group, that owns the bus whose
+key is stored in the file @var{PATHNAME}, to the specified
+group. The group can be specified either with a numerical
+group identifier or with a group name.
+
+The current ownership of the bus can be retrieved by
+running @command{stat} over the file @var{PATHNAME}.
+
+
+
+@node Protocol
+@chapter Protocol
+
+@command{bus} is built upon following three procedures.
+
+@noindent
+@code{create}
+@example
+@w{@xrm{}Select a filename.@xtt{}}
+
+@w{@xrm{}Create XSI semaphore array @{@code{S} = 0, @code{W} = 0, @code{X} = 1, @code{Q} = 0, @code{N} = 0@}@xtt{}}
+@w{@xrm{}with random key. Store the semaphore array's key in decimal form@xtt{}}
+@w{@xrm{}on the first line in the selected file.@xtt{}}
+
+@w{@xrm{}Create XSI shared memory, with an allocation of 2048 bytes, with@xtt{}}
+@w{@xrm{}a random key. Store the shared memory's key in decimal form on@xtt{}}
+@w{@xrm{}the second line in the selected file.@xtt{}}
+@end example
+
+@noindent
+@code{broadcast}
+@example
+with P(X):
+  Z(W)
+  @w{@xrm{}Write NUL-terminate message to shared memory@xtt{}}
+  with V(N): -- (1)
+    Q := 0
+    Z(S)
+
+-- (1) @w{@xrm{}may be omitted if semaphores are known that@xtt{}}
+   @w{P()@xrm{}, @xtt{}Z()@xrm{}, @xtt{}V()@xrm{} cannot create a race condition@xtt{}}
+   @w{@xrm{}with a processes running @xtt{}Z()@xrm{}.@xtt{}}
+@end example
+
+@noindent
+@code{listen}
+@example
+with V(S):
+  forever:
+    V(Q)
+    Z(Q)
+    @w{@xrm{}Read NUL-terminated message from shared memory@xtt{}}
+    if breaking:
+      break
+    with V(W):
+      with P(S):
+        Z(S)
+        Z(N)
+@end example
+
+@noindent
+@code{V(a)} means that semaphore a is released.@*
+@code{P(a)} means that semaphore a is acquired.@*
+@code{Z(a)} means that the process waits for semaphore a to become 0.@*
+@code{with P(a)} that @code{P(a)} is done before the entering the scope,
+and @code{V(a)} is done when exiting the scope. It also means that
+these actions [@code{P(a)} and @code{V(a)}] are undone when the process
+exits, or if the call fails.@*
+@code{with V(a)} is to @code{V(a)} as @code{with P(a)} is to @code{P(a)}.
+
+
+
+@node Rationale
+@chapter Rationale
+
+We need an interprocess communication system similar to message queues.
+But we need broadcasting rather than anycasting, so we have a fast,
+simple and daemonless system for announcing events to any processes that
+might be interested.
+
+
+
+@node GNU Free Documentation License
+@appendix GNU Free Documentation License
+@include fdl.texinfo
+
+@bye
+
diff --git a/doc/info/fdl.texinfo b/doc/info/fdl.texinfo
new file mode 100644
index 0000000..cb71f05
--- /dev/null
+++ b/doc/info/fdl.texinfo
@@ -0,0 +1,505 @@
+@c The GNU Free Documentation License.
+@center Version 1.3, 3 November 2008
+
+@c This file is intended to be included within another document,
+@c hence no sectioning command or @node.
+
+@display
+Copyright @copyright{} 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
+@uref{http://fsf.org/}
+
+Everyone is permitted to copy and distribute verbatim copies
+of this license document, but changing it is not allowed.
+@end display
+
+@enumerate 0
+@item
+PREAMBLE
+
+The purpose of this License is to make a manual, textbook, or other
+functional and useful document @dfn{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.
+
+@item
+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, 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, La@TeX{} 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.
+
+The ``publisher'' means any person or entity that distributes copies
+of the Document to the public.
+
+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.
+
+@item
+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.
+
+@item
+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.
+
+@item
+MODIFICATIONS
+
+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:
+
+@enumerate A
+@item
+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.
+
+@item
+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.
+
+@item
+State on the Title page the name of the publisher of the
+Modified Version, as the publisher.
+
+@item
+Preserve all the copyright notices of the Document.
+
+@item
+Add an appropriate copyright notice for your modifications
+adjacent to the other copyright notices.
+
+@item
+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.
+
+@item
+Preserve in that license notice the full lists of Invariant Sections
+and required Cover Texts given in the Document's license notice.
+
+@item
+Include an unaltered copy of this License.
+
+@item
+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.
+
+@item
+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.
+
+@item
+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.
+
+@item
+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.
+
+@item
+Delete any section Entitled ``Endorsements''.  Such a section
+may not be included in the Modified Version.
+
+@item
+Do not retitle any existing section to be Entitled ``Endorsements'' or
+to conflict in title with any Invariant Section.
+
+@item
+Preserve any Warranty Disclaimers.
+@end enumerate
+
+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.
+
+@item
+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.''
+
+@item
+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.
+
+@item
+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.
+
+@item
+TRANSLATION
+
+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.
+
+@item
+TERMINATION
+
+You may not copy, modify, sublicense, or distribute the Document
+except as expressly provided under this License.  Any attempt
+otherwise to copy, modify, sublicense, or distribute it is void, and
+will automatically terminate your rights under this License.
+
+However, if you cease all violation of this License, then your license
+from a particular copyright holder is reinstated (a) provisionally,
+unless and until the copyright holder explicitly and finally
+terminates your license, and (b) permanently, if the copyright holder
+fails to notify you of the violation by some reasonable means prior to
+60 days after the cessation.
+
+Moreover, your license from a particular copyright holder is
+reinstated permanently if the copyright holder notifies you of the
+violation by some reasonable means, this is the first time you have
+received notice of violation of this License (for any work) from that
+copyright holder, and you cure the violation prior to 30 days after
+your receipt of the notice.
+
+Termination of your rights under this section does not terminate the
+licenses of parties who have received copies or rights from you under
+this License.  If your rights have been terminated and not permanently
+reinstated, receipt of a copy of some or all of the same material does
+not give you any rights to use it.
+
+@item
+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
+@uref{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.  If the Document
+specifies that a proxy can decide which future versions of this
+License can be used, that proxy's public statement of acceptance of a
+version permanently authorizes you to choose that version for the
+Document.
+
+@item
+RELICENSING
+
+``Massive Multiauthor Collaboration Site'' (or ``MMC Site'') means any
+World Wide Web server that publishes copyrightable works and also
+provides prominent facilities for anybody to edit those works.  A
+public wiki that anybody can edit is an example of such a server.  A
+``Massive Multiauthor Collaboration'' (or ``MMC'') contained in the
+site means any set of copyrightable works thus published on the MMC
+site.
+
+``CC-BY-SA'' means the Creative Commons Attribution-Share Alike 3.0
+license published by Creative Commons Corporation, a not-for-profit
+corporation with a principal place of business in San Francisco,
+California, as well as future copyleft versions of that license
+published by that same organization.
+
+``Incorporate'' means to publish or republish a Document, in whole or
+in part, as part of another Document.
+
+An MMC is ``eligible for relicensing'' if it is licensed under this
+License, and if all works that were first published under this License
+somewhere other than this MMC, and subsequently incorporated in whole
+or in part into the MMC, (1) had no cover texts or invariant sections,
+and (2) were thus incorporated prior to November 1, 2008.
+
+The operator of an MMC Site may republish an MMC contained in the site
+under CC-BY-SA on the same site at any time before August 1, 2009,
+provided the MMC is eligible for relicensing.
+
+@end enumerate
+
+@page
+@heading 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:
+
+@smallexample
+@group
+  Copyright (C)  @var{year}  @var{your name}.
+  Permission is granted to copy, distribute and/or modify this document
+  under the terms of the GNU Free Documentation License, Version 1.3
+  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''.
+@end group
+@end smallexample
+
+If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
+replace the ``with@dots{}Texts.''@: line with this:
+
+@smallexample
+@group
+    with the Invariant Sections being @var{list their titles}, with
+    the Front-Cover Texts being @var{list}, and with the Back-Cover Texts
+    being @var{list}.
+@end group
+@end smallexample
+
+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.
+
+@c Local Variables:
+@c ispell-local-pdict: "ispell-dict"
+@c End: