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Linux Optimized Link State Routing Protocol (OLSR) IPv6 HOWTO

Lars Strand

<lars (at) unik no>

Revision History                                                             
Revision 1.0           2004-04-23            Revised by: EJH                 
Final review complete. Document published to the LDP collection.             
Revision 0.6           2004-04-19            Revised by: LKS                 
Thanks to Thomas Zimmerman <thomas (at) zimres net> for a language review!   
Updated to latest version number and added a section on plugin-support in    
OLSRd. Changed lisence back to [] GFDL   
Revision 0.5           2004-03-08            Revised by: LKS                 
An almost complete rewrite. Adding OLSRd (old uOLSR), updated to RFC3626.    
Removed NROLSR and CRCOLSR. Converted to XML Docbook. Changed the license    
from GFDL to [] OPL due to some GFDL      
[] problems.      
Revision 0.3           2003-08-05            Revised by: LKS                 
Initial release.                                                             

  This document describes the software and procedures to set up and use 
Optimized Link State Routing Protocol (OLSR) with IPv6 for Linux. OLSR is
used as a routing protocol for Mobile Ad-Hoc Networks ([
rfc/rfc2501.txt] MANET) (also called "spontaneous network").

Table of Contents
1. Introduction
    1.1. Why Ad-Hoc network?
    1.2. What is a MANET?
    1.3. What is Optimized Link State Routing (OLSR)?
    1.4. How does OLSR work?
    1.5. What about IBSS (IEEE ad-hoc mode)?
2. IPv6
3. OLSR for Linux
    3.1. Installing OLSRd
    3.2. Using OLSRd
    3.3. What about HNA messages?
    3.4. Plugin support
    3.5. Optional GUI
    3.6. Other OLSR implementations
4. FAQ
5. Useful Resources
6. Copyright, acknowledgments and miscellaneous
    6.1. Copyright and License
    6.2. How this document was produced
    6.3. Feedback
    6.4. Acknowledgments
A. GNU Free Documentation License
    A.12. ADDENDUM: How to use this License for your documents

1. Introduction

  This document describes the software and procedures to set up and use
Optimized Link State Routing Protocol (OLSR) with IPv6 for Linux.

1.1. Why Ad-Hoc network?

  An English translation of ad-hoc is "For a particular purpose (improvised,
made up in an instant)" (source: [
List_of_Latin_phrases#A] Wikipedia). An Ad-hoc network, or "spontaneous
network", is especially useful when dealing with wireless devices in which
some of the devices are part of the network only for the duration of a
communications session and the need for a dynamic network topology is
eminent. A "Mobile Ad hoc Network" is usually called a MANET.

1.2. What is a MANET?

" A MANET consists of mobile platforms (e.g., a router with multiple hosts
and wireless communications devices)--herein simply referred to as 'nodes'
--which are free to move about arbitrarily. The nodes may be located in or on
airplanes, ships, trucks, cars, perhaps even on people or very small devices,
and there may be multiple hosts per router. A MANET is an autonomous system
of mobile nodes. The system may operate in isolation, or may have gateways to
and interface with a fixed network." --- RFC2501: Mobile Ad hoc Networking
(MANET), section 3 (page 3).

1.3. What is Optimized Link State Routing (OLSR)?

  "OLSR is a proactive routing protocol for mobile ad hoc networks. The
protocol inherits the stability of a link state algorithm and has the
advantage of having routes immediately available when needed due to its
proactive nature. OLSR is an optimization over the classical link state
protocol, tailored for mobile ad hoc networks."

  "OLSR is designed to work in a completely distributed manner and does not
depend on any central entity. The protocol does NOT REQUIRE reliable
transmission of control messages: each node sends control messages
periodically, and can therefore sustain a reasonable loss of some such
messages. Such losses occur frequently in radio networks due to collisions or
other transmission problems." --- RFC3626: OLSR, section 1.3 (page 8)

1.4. How does OLSR work?

"The Optimized Link State Routing Protocol (OLSR) is developed for mobile ad
hoc networks. It operates as a table driven, proactive protocol, i.e.,
exchanges topology information with other nodes of the network regularly.
Each node selects a set of its neighbor nodes as 'multi-point relays' (MPR).
In OLSR, only nodes, selected as such MPRs, are responsible for forwarding
control traffic, intended for diffusion into the entire network. MPRs provide
an efficient mechanism for flooding control traffic by reducing the number of
transmissions required." --- RFC3626: OLSR, section 1 (page 4)

1.5. What about IBSS (IEEE ad-hoc mode)?

The IEEE 802.11 standard defines two modes:


IEEE 802.11 standard

 1. Infrastructure mode: The wireless network consist of at least one access
    point (AP) connected to the wired network and a set of wireless nodes
    (WN). This configuration is called a Basic Service Set (BSS). Extended
    Service Set (ESS) is a set of two or more BSSs (multiple cells).
 2. Ad hoc mode: Also called "IEEE ad-hoc mode" or "peer-to-peer mode". This
    configuration is called Independent Basic Service Set (IBSS) and is
    useful for establishing a network where wireless infrastructure does not
    exist or where services are not required.

  So why use OLSR when we can use "IEEE ad-hoc mode"? IEEE ad-hoc mode does
NOT support multi-hop. See figure below


"IEEE 8102.11 Ad hoc" mode has no support for multihop, something OLSR does

2. IPv6

IP version 6 (IPv6) is a new version of the Internet Protocol, designed as
the successor to IP version 4 (IPv4) []
[RFC-791]. The changes from IPv4 to IPv6 fall primarily into the following

��*�Expanded addressing capabilities
��*�Header format simplification
��*�Improved support for extensions and options
��*�Flow labeling capability
��*�Authentication and privacy capabilities

For more information on IPv6 in general, visit the IETF's IPv6 Working Group.

3. OLSR for Linux

  There are several OLSR implementation for Linux, but not all of them
support IPv6. You should know how to enable and use IPv6 on Linux. Peter
Bieringer has written an excellent Linux IPv6 HOWTO.

  There is one OLSR implementation that is becoming the "standard" and most
widely used. It goes by the descriptive name "OLSRd" (old Unik-OLSR).

  OLSRd is an implementation based on the INRA C code, but has been almost
completely rewritten, so there is not much left of the original INRA code
(that mean it almost GPL). OLSRd also is under very rapid development, and if
you report in a bug, it is usually fixed in a matter of hours.

  OLSRd [] fully comply to the OLSR
RFC, support for plugins, and it has an optional GUI interface (to see what's
going on). The implementation also has a informative "up-to-date" [http://] web-page with links to mailing lists and papers.

3.1. Installing OLSRd

There are up-to multiple new releases of OLSRd each month, so check the OLSRd
[] web-site for the newest release.


 1. The latest release as of this writing is 0.4.3, but by the time you read
    this there is almost certain a new release. Fetch the latest release from
 2. Unpack, compile and install the source code:
          # tar jxvf uolsrd-x.y.z                                            
          # cd unik-olsrd-x.y.z                                              
          # make                                                             
          # make install                                                     
 3. The olsrd gets installed to /usr/bin/ and a default config file,
    olsrd.conf can be found under /etc

Check out the /etc/olsrd.conf config file, and change values to fit your
system. All values in this file can be overridden with command line options
to olsrd. The main options to change are:

    # Debug level(0-9)                                                       
    # If set to 0 the daemon runs in the background                          
    DEBUG           1                                                        
    # IP version to use (4 or 6)                                             
    IPVERSION       6                                                        
    # A list of whitespace separated interface names                         
    INTERFACES      eth1                                                     

  Later on, when you know OLSRd is configured correctly, you may set "DEBUG"
to 0 to make it run in the background. You may then also add it to your init
scripts. But to test that everything first, set this to at least 1 (setting
this higher will produce a lot more info messages on APM, forwarding, parsing
of the config file etc.)

3.2. Using OLSRd

3.2.1. On one host

When OLSRd is installed and configured, it can be started as root with:
      # olsrd                                                                

All the settings in /etc/olsrd.conf can be overridden by command line
      # olsrd -i eth1 -ipv6 -d 1                                             

Would start olsrd listening on interface eth1 using IPv6 and with debug

We start olsrd:
    # olsrd -i eth1 -d 1 -ipv6                                               
       *** UniK olsrd-0.4.3 ***                                              
    hello interval = 2.00       hello int nonwireless: = 4.00 (1)            
    tc interval = 5.00          polling interval = 0.10                      
    neighbor_hold_time = 6.00   neighbor_hold_time_nw = 12.00                
    topology_hold_time = 15.00  tos setting = 16                             
    hna_interval = 15.00         mid_interval = 5.00                         
    Willingness set to 3 - next update in 20.000000 secs                     
    Using IP version 6                                                       
    Using multicast address ff05::15                                         
     ---- Interface configuration ----                                       
     eth1:                                          (2)                      
            Address: fec0:106:2700::10                                       
            Multicast: ff05::15                                              
            Interface eth1 set up for use with index 0                       
     Main address: fec0:106:2700::10                (3)                      
     NEIGHBORS: l=linkstate, m=MPR, w=willingness                            
     Thread created - polling every 0.10 seconds    (4)                      
     neighbor list: 11:43:17.214807                                          
     neighbor list: 11:43:19.194967                                          
     neighbor list: 11:43:21.395046                                          
     neighbor list: 11:43:23.604800                                          
     neighbor list: 11:43:25.694875                                          

(1) This shows all the settings OLSRd is using. You may override these by
    either specifying it in the config file (/etc/olsrd.conf) or specify it
    at the command line. Read the [] OLSR
    RFC for a description on what all these settings means.
(2) OLSRd found our interface. If you are using OLSRd with multiple
    interfaces, "Multiple Interface Declaration" (MID) messages will be
(3) If you are using OLSRd with multiple interfaces, it will pick the first
    interface specified as the "main" address.
(4) Since no other hosts are running OLSRd, this list is empty.

Another thing worth noticing, is that an entry is added to our routing table:
    # route -A inet6                                                         
    Destination:   Next Hop   Flags  Metric  Ref  Use Iface                  
    ff05::15/128   ff05::15   UAC    0       1    1   eth1                   

This is the IPv6 multicast address OLSR is using to talk to other nodes
running OLSR.

3.2.2. Adding other hosts

There is no point in using OLSRd on only one node, so we add some nodes. You
will then see the "neighbor list" gets updated:
  neighbor list: 12:55:14.733586                                             
  neighbor list: 12:55:18.803585                                             
  Willingness for fec0:106:2700::11 changed from 0 to 3 - UPDATING  (1)      
  neighbor list: 12:55:22.763585                                             
  fec0:106:2700::11:l=0:m=0:w=3[2hlist:]                            (2)      
  neighbor list: 12:55:26.833589                                             
  Willingness for fec0:106:2700::12 changed from 0 to 2 - UPDATING  (3)      
  neighbor list: 12:55:30.903585                                             
  neighbor list: 12:55:34.863585                                             
  neighbor list: 12:55:39.153586                                             
  fec0:106:2700::12:l=1:m=0:w=2[2hlist:fec0:106:2700::11:]          (4)      
  fec0:106:2700::11:l=1:m=0:w=3[2hlist:fec0:106:2700::12:]          (5)      
  neighbor list: 12:55:43.443605                                             

(1)   Another node detected (node B). This specifies the willingness of a
    node to carry and forward traffic for other nodes. Here the new node 
    fec0:106:2700::11 is willing to forward traffic. A host with low battery
    may not be willing to forward large amount of traffic, - so it will
    proclaim a lower willingness value (routing based on powerstatus is
    available as a plugin).
(2)   The node has been added to our routing table. We can not (yet) reach
    any other node by way of this node, since the 2-hop neighbor list (
    [2hlist:]) is empty. A 2-hop neighbor is a node heard by a neighbor.
(3)   Here is a third node (node C) running OLSRd.
(4)   After a short time, when all nodes have been updated and routes
    calculated, we may also reach any of the other nodes via the other. The
    2-hop neighbor list ([2hlist:]) is populated: We can reach node B via C.
(5)   Here we can reach node C via B.

You will also see the routing table is updated with the new hosts:
    # route -A inet6                                                         
    Destination:           Next Hop   Flags  Metric  Ref  Use Iface          
    fec0:106:2700::11/128  ::         UH     1       0    0   eth1           
    fec0:106:2700::12/128  ::         UH     1       0    0   eth1           

  The real beauty of OLSR is when you add a bunch of nodes and move them
around. You can still reach each one of them either directly (if they are
close), or through other nodes.

3.2.3. Movement

  When every node can reach every other node, it's no fun. Let's start moving
the nodes, so that node "A" and "B" are out of (radio) range of each other.
So when we move node "A" far enough away so that it can't hear node "C", all
traffic must go through node "B":


We move our three nodes so that node A and C must speak through node B to
reach each other.

  Tip: Instead of physically moving the nodes around, you can use ip6tables.
You can drop all packet using the MAC-address. You just need to block on one
   # ip6tables -A INPUT -m mac --mac-source XX:XX:XX:XX:XX:XX -j DROP        

  The output from OLSRd on host A is then:
  neighbor list: 13:22:35.693587                                             
  fec0:106:2700::11:l=1:m=1:w=3[2hlist:fec0:106:2700::12:]  (1)              
  neighbor list: 13:22:40.093588                                             
  neighbor list: 13:22:44.053594                                             
  neighbor list: 13:22:48.233594                                             
  neighbor list: 13:22:52.193605                                             

(1)   We can reach node B directly, and via node B we can reach node C.

  The routing table also gets updated. For node A to reach node C it must go
through node B:
    # route -A inet6                                                          
    Destination:             Next Hop           Flags  Metric  Ref  Use Iface 
    fec0:106:2700::11/128    ::                 UH      1      1    0   eth1  
    fec0:106:2700::12/128    fec0:106:2700::11  UGH     2      0    0   eth1  

3.3. What about HNA messages?

" In order to provide this capability of injecting external routing
information into an OLSR MANET, a node with such non-MANET interfaces
periodically issues a Host and Network Association (HNA) message, containing
sufficient information for the recipients to construct an appropriate routing

" An example of such a situation could be where a node is equipped with a
fixed network (e.g., an Ethernet) connecting to a larger network as well as a
wireless network interface running OLSR." --- RFC3626: OLSR, section 12 (page


OLSR with a gateway (GW), that sends out HNA messages. All the other nodes
may then be accessing the "Internet"

  To have one node, act as a gateway and send out HNA messages, you must
change the HNA6 in /etc/olsrd.conf:
    # HNA IPv6 routes                                                        
    # syntax: netaddr prefix                                                 
    # Example Internet gateway                                               
    HNA6 :: 0                                                                

  When you start OLSRd, you will see the node is sending out HNA messages
    Sending HNA (48 bytes)...                                                

  When the other nodes receives a HNA message, they update their routing
      # route -A inet6                                                          
      Destination:             Next Hop           Flags  Metric  Ref  Use Iface 
      ::/0                     fec0:106:2700::1   UG     1       0    0   eth1  

  You may also have multiple nodes in a MANET to act as gateways (sending out
HNA messages). Each mobile node then use the nearest gateway.

3.4. Plugin support

As of version 0.4.3 OLSRd also support plugins. Plugins may be used to add
extended functionality in a MANET. If only a subset of the nodes knows how to
interpret the messagetype, it will be forwarded by all the nodes by the 
"default forwarding algorithm" (see section 3.4.1 in the [
/rfc3626.txt] OLSR RFC). This way certain nodes may add special functionlity
into OLSR.

As of this writing, two example plugins is included in the OLSRd release. One
of these plugins add routing based on powerstatus. If one node has low
battery, it can set its willingness lower and traffic may be routed through
other nodes.

3.5. Optional GUI

  OLSRd also has an optional GUI, which can show a list of available nodes
and grab packets. To compile the GUI front end, you must have GTK2. In
unik-olsrd-x.y.z directory do:
     # cd front-end                                                          
     # make                                                                  
     # make install                                                          

Note Remember to start OLSRd with the -ipc switch or set IPC-CONNECT yes in /
     etc/olsrd.conf to enable the GUI to chat with OLSRd.                    

  To see some examples of the use of GUI, check out [

3.6. Other OLSR implementations

There is also other OLSR implementations, none have gained as much popularity
as OLSRd, and none of them (except [] QOLSR?) are fully
RFC compliant.

3.6.1. INRIA

INRIA was one of the first(?) implementation of OLSR [http://] Their
web-site has not been updated for quite a while, and the OLSR code you can
download only complies to draft-ietf-manet-olsr-03.txt (it's now an RFC).
There is suppose to be another more up-to-date version of INRIA olsr, but I
have not found it. INRIA OLSR does not support IPv6.

3.6.2. NROLSR

The "US Naval Research Laboratory" (NRL) also has an OLSR implementation. It
is written in C++, and has IPv6 support. [

3.6.3. CRCOLSR

CRCOLSR is a implementation based on the French INRIA code. It is is supposed
to be maintained by "Communication Research Center" (CRC) in Canada. But as
of this writing, there have been no new releases since April 3, 2003. [http:/

3.6.4. QOLSR

QOLSR is aiming to provide "Quality of Service" routing in wireless mobile ad
hoc networks. There is no QoS support at the time of this writing, and
support for ipv4/ipv6 is triggered at compile time. Written in C++.

4. FAQ

Some of these question/answers are from the [] OLSRd site.

4.1. If OLSRd fully RFC3626 compliant?
4.2. Can I mix site-local and global IPv6 addresses?
4.3. The GUI front-end failed to compile...why?
4.4. If there is multiply gateways present, how does the mobile node conclude
    to use the nearest one?
4.5. I get OLSRd up and running - but the nodes don't seem to "hear" each

4.1. If OLSRd fully RFC3626 compliant?

Yes. It even has implemented some of the extra functionality mentioned in the
RFC. See the []   RFC Compliance
section for complete list.

4.2. Can I mix site-local and global IPv6 addresses?

Yes. But keep in mind that they intentionally were not designed to be used at
the same time. The network topology can be quite "messy" if you start using
these two.

4.3. The GUI front-end failed to compile...why?

You probably don't have the GTK2.0 development libraries installed.

4.4. If there is multiply gateways present, how does the mobile node conclude
to use the nearest one?

When a new gateway is detected, the Mobile Node checks the distance (number
of hops) to this newly discovered gateway compared to the current gateway. If
there is a shorter distance, this new gateway becomes the current (default)
gateway. See section 12.6.2 in the OLSR RFC ([
rfc3626.txt] RFC3626)

4.5. I get OLSRd up and running - but the nodes don't seem to "hear" each

Most of the time this is a configuration error: Check the following:

��*�  If using WLAN interfaces make sure the ESSID/key match.
��*�  Make sure the cards are set in "ad-hoc" mode and not "managed".
��*�  Make sure you are not blocking UDP/698. If using netfilter run 
    ip6tables -L as root to see what rules are set. ip6tables -F flushes all

5. Useful Resources


 1. OLSRd (old uOLSR)[]
 2. Optimized Link State Routing Protocol (OLSR) RFC3626[
 3. Mobile Ad hoc Networking (MANET) RFC2501[
 4. Mobile Ad-hoc Networks (manet) Working Group (IETF)[
 5. Open Shortest Path First IGP (ospf)[
 6. Protean Forge - OLSR software (CRC and NRL) [
 8. QOLSR []
 9. IPv6 Working Group (IETF) [
10. RFC2460 Internet Protocol, Version 6 (IPv6) Specification [http://]
11. Peter Bieringer's Linux IPv6 HOWTO (en) [
12. Current Status of IPv6 Support for Networking Applications [http://]   http://

6. Copyright, acknowledgments and miscellaneous

6.1. Copyright and License

Copyright (c) 2003, 2004 Lars Strand.

  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".

6.2. How this document was produced

This document was originally written in LaTeX using Emacs. HTML version
created with latex2html. Later it was converted to DocBook XML.

An up-to-date version of this document can be found at:

HTML: []   http://

6.3. Feedback

Suggestions, corrections, additions wanted. Contributors wanted and
acknowledged. Flames not wanted.

I can always be reached at <lars at unik no>

Homepage: []

6.4. Acknowledgments

This document was produced as a part of Interoperable Networks for Secure
Communications [] (INSC task 6)

Thanks to Andreas Hafslund (andreha [at] unik no) for initial support. Also
thanks to UniK (University Graduate Center) [] http:// and FFI (Norwegian Defence Research Establishment) [http://] for hardware support.

Also thanks to Andreas T�nnesen (andreto [at] unik no) for technical help
updating this howto

Thanks also to the other HOWTO authors whose works I have referenced:

Linux IPv6 HOWTO (en) by Peter Bieringer

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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
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You may also lend copies, under the same conditions stated above, and you may
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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
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Copying with changes limited to the covers, as long as they preserve the
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If the required texts for either cover are too voluminous to fit legibly, you
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If you publish or distribute Opaque copies of the Document numbering more
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It is requested, but not required, that you contact the authors of the
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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 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,
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    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
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 K. For any section Entitled "Acknowledgements" or "Dedications", Preserve
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 M. Delete any section Entitled "Endorsements". Such a section may not be
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 N. Do not retitle any existing section to be Entitled "Endorsements" or to
    conflict in title with any Invariant Section.
 O. Preserve any Warranty Disclaimers.

If the Modified Version includes new front-matter sections or appendices that
qualify as Secondary Sections and contain no material copied from the
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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,
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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
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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,
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one, on explicit permission from the previous publisher that added the old

The author(s) and publisher(s) of the Document do not by this License give
permission to use their names for publicity for or to assert or imply
endorsement of any Modified Version.


You may combine the Document with other documents released under this
License, under the terms defined in section 4 above for modified versions,
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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".


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.


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.


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.


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.


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

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
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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.

A.12. ADDENDUM: How to use this License for your documents

To use this License in a document you have written, include a copy of the
License in the document and put the following copyright and license notices
just after the title page:

      Copyright (c) YEAR YOUR NAME. Permission is granted to copy, distribute
    and/or modify this document under the terms of the GNU Free Documentation
    License, Version 1.2 or any later version published by the Free Software
    Foundation; with no Invariant Sections, no Front-Cover Texts, and no
    Back-Cover Texts. A copy of the license is included in the section
    entitled "GNU Free Documentation License".
If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
replace the "with...Texts." line with this:

      with the Invariant Sections being LIST THEIR TITLES, with the
    Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
If you have Invariant Sections without Cover Texts, or some other combination
of the three, merge those two alternatives to suit the situation.

If your document contains nontrivial examples of program code, we recommend
releasing these examples in parallel under your choice of free software
license, such as the GNU General Public License, to permit their use in free

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