ERC

This manual is for ERC as distributed with Emacs 28.2.

Copyright © 2005–2022 Free Software Foundation, Inc.

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 the Front-Cover Texts being “A GNU Manual,” and with the Back-Cover Texts as in (a) below. A copy of the license is included in the section entitled “GNU Free Documentation License”.

(a) The FSF’s Back-Cover Text is: “You have the freedom to copy and modify this GNU manual.”

All Emacs Lisp code contained in this document may be used, distributed, and modified without restriction.

Table of Contents


1 Introduction

ERC is a powerful, modular, and extensible IRC client for Emacs. It is distributed with Emacs since version 22.1.

It comes with the following capabilities enabled by default.


2 Getting Started

The command M-x erc will start ERC and prompt for the server to connect to.

If you want to place ERC settings in their own file, you can place them in ~/.emacs.d/.ercrc.el, creating it if necessary.

If you would rather use the Customize interface to change how ERC works, do M-x customize-group RET erc RET. In particular, ERC comes with lots of modules that may be enabled or disabled; to select which ones you want, do M-x customize-variable RET erc-modules RET.


2.1 Sample Session

This is an example ERC session which shows how to connect to the ‘#emacs’ channel on Libera.Chat. Another IRC channel on Libera.Chat that may be of interest is ‘#erc’, which is a channel where ERC users and developers hang out. These channels used to live on the Freenode IRC network until June 2021, when they—along with the official IRC channels of the GNU Project, the Free Software Foundation, and many other free software communities—relocated to the Libera.Chat network in the aftermath of changes in governance and policies of Freenode in May and June 2021. GNU and FSF’s announcements about this are at https://lists.gnu.org/archive/html/info-gnu/2021-06/msg00005.html, https://lists.gnu.org/archive/html/info-gnu/2021-06/msg00007.html, and https://lists.gnu.org/archive/html/info-gnu-emacs/2021-06/msg00000.html.

  • Connect to Libera.Chat

    Run M-x erc. Use “irc.libera.chat” as the IRC server, “6667” as the port, and choose a nickname.

  • Get used to the interface

    Switch to the “irc.libera.chat:6667” buffer, if you’re not already there. You will see first some messages about checking for ident, and then a bunch of other messages that describe the current IRC server.

  • Join the #emacs channel

    In that buffer, type “/join SPC #emacs” and hit RET. Depending on how you’ve set up ERC, either a new buffer for “#emacs” will be displayed, or a new buffer called “#emacs” will be created in the background. If the latter, switch to the “#emacs” buffer. You will see the channel topic and a list of the people who are currently on the channel.

  • Register your nickname with Libera.Chat

    If you would like to be able to talk with people privately on the Libera.Chat network, you will have to “register” your nickname. To do so, switch to the “irc.libera.chat:6667” buffer and type “/msg NickServ register <password>”, replacing “<password>” with your desired password. It should tell you that the operation was successful.

  • Talk to people in the channel

    If you switch back to the “#emacs” buffer, you can type a message, and everyone on the channel will see it.

  • Open a query buffer to talk to someone

    If you want to talk with someone in private (this should usually not be done for technical help, only for personal questions), type “/query <nick>”, replacing “<nick>” with the nickname of the person you would like to talk to. Depending on how ERC is set up, you will either see a new buffer with the name of the person, or such a buffer will be created in the background and you will have to switch to it. Begin typing messages, and you will be able to have a conversation.

    Note that if the other person is not registered, you will not be able to talk with them.


2.2 Special Features

ERC has some features that distinguish it from some IRC clients.

  • multiple channels and multiple servers

    Every channel is put in a separate buffer. Several IRC servers may be connected to at the same time.

  • private message separation

    Private conversations are treated as channels, and are put into separate buffers in Emacs. We call these “query buffers”.

  • highlighting

    Some occurrences of words can be highlighted, which makes it easier to track different kinds of conversations.

  • notification

    ERC can notify you that certain users are online.

  • channel tracking

    Channels can be hidden and conversation continue in the background. You are notified when something is said in such a channel that is not currently visible. This makes it easy to get Real Work done while still maintaining an IRC presence.

  • nick completion

    ERC can complete words upon hitting TAB, which eases the writing of nicknames in messages.

  • history

    Past actions are kept in history rings for future use. To navigate a history ring, hit M-p to go backwards and M-n to go forwards.

  • multiple languages

    Different channels and servers may have different language encodings.

    multiple languages. Please contact the Emacs developers if you are interested in helping with the translation effort.

  • user scripting

    Users can load scripts (e.g., auto greeting scripts) when ERC starts up.

    It is also possible to make custom IRC commands, if you know a little Emacs Lisp. Just make an Emacs Lisp function and call it erc-cmd-NEWCOMMAND, where NEWCOMMAND is the name of the new command in capital letters.

  • auto reconnect

    If the connection goes away at some point, ERC will try to reconnect automatically. If it fails to reconnect, and you want to try to manually reestablish the connection at some later point, switch to an ERC buffer and run the /RECONNECT command.


3 Keys Used in ERC

This is a summary of keystrokes available in every ERC buffer.

C-a or <home> (erc-bol)

Go to beginning of line or end of prompt.

RET (erc-send-current-line)

Send the current line

TAB (completion-at-point or erc-button-next)

If at prompt, complete the current word. Otherwise, move to the next link or button.

M-TAB (ispell-complete-word)

Complete the given word, using ispell.

C-c C-a (erc-bol)

Go to beginning of line or end of prompt.

C-c C-b (erc-switch-to-buffer)

Use read-buffer to prompt for a ERC buffer to switch to.

C-c C-c (erc-toggle-interpret-controls)

Toggle interpretation of control sequences in messages.

C-c C-d (erc-input-action)

Interactively input a user action and send it to IRC.

C-c C-e (erc-toggle-ctcp-autoresponse)

Toggle automatic CTCP replies (like VERSION and PING).

C-c C-f (erc-toggle-flood-control)

Toggle use of flood control on sent messages.

C-c TAB (erc-invite-only-mode)

Turn on the invite only mode (+i) for the current channel.

C-c C-j (erc-join-channel)

Join channel. If point is at the beginning of a channel name, use that as default.

C-c C-k (erc-go-to-log-matches-buffer)

Interactively open an erc-log-matches buffer

C-c C-l (erc-save-buffer-in-logs)

Append buffer contents to the log file, if logging is enabled.

C-c C-n (erc-channel-names)

Run "/names #channel" in the current channel.

C-c C-o (erc-get-channel-mode-from-keypress)

Read a key sequence and call the corresponding channel mode function. After doing C-c C-o, type in a channel mode letter.

C-g means quit. RET lets you type more than one mode at a time. If l is pressed, erc-set-channel-limit gets called. If k is pressed, erc-set-channel-key gets called. Anything else will be sent to erc-toggle-channel-mode.

C-c C-p (erc-part-from-channel)

Part from the current channel and prompt for a reason.

C-c C-q (erc-quit-server)

Disconnect from current server after prompting for reason.

C-c C-r (erc-remove-text-properties-region)

Clears the region (start,end) in object from all colors, etc.

C-c C-t (erc-set-topic)

Prompt for a topic for the current channel.

C-c C-u (erc-kill-input)

Kill current input line using erc-bol followed by kill-line.


4 Modules

One way to add functionality to ERC is to customize which of its many modules are loaded.

There is a spiffy customize interface, which may be reached by typing M-x customize-option RET erc-modules RET. Alternatively, set erc-modules manually and then call erc-update-modules.

The following is a list of available modules.

autoaway

Set away status automatically

autojoin

Join channels automatically

bbdb

Integrate with the Big Brother Database

button

Buttonize URLs, nicknames, and other text

capab-identify

Mark unidentified users on freenode and other servers supporting CAPAB.

completion (aka pcomplete)

Complete nicknames and commands (programmable)

fill

Wrap long lines

identd

Launch an identd server on port 8113

irccontrols

Highlight or remove IRC control characters

log

Save buffers in logs

match

Highlight pals, fools, and other keywords

menu

Display a menu in ERC buffers

netsplit

Detect netsplits

noncommands

Don’t display non-IRC commands after evaluation

notify

Notify when the online status of certain users changes

notifications

Send you a notification when you get a private message, or your nickname is mentioned

page

Process CTCP PAGE requests from IRC

readonly

Make displayed lines read-only

replace

Replace text in messages

ring

Enable an input history

scrolltobottom

Scroll to the bottom of the buffer

services

Identify to Nickserv (IRC Services) automatically

smiley

Convert smileys to pretty icons

sound

Play sounds when you receive CTCP SOUND requests

spelling

Check spelling of messages

stamp

Add timestamps to messages

track

Track channel activity in the mode-line

truncate

Truncate buffers to a certain size

unmorse

Translate morse code in messages


5 Advanced Usage


5.1 Connecting to an IRC Server

The easiest way to connect to an IRC server is to call M-x erc. If you want to assign this function to a keystroke, the following will help you figure out its parameters.

Function: erc

Select connection parameters and run ERC. Non-interactively, it takes the following keyword arguments.

  • server
  • port
  • nick
  • password
  • full-name

That is, if called with the following arguments, server and full-name will be set to those values, whereas erc-compute-port and erc-compute-nick will be invoked for the values of the other parameters.

(erc :server "irc.libera.chat" :full-name "J. Random Hacker")

To connect securely over an encrypted TLS connection, use M-x erc-tls.

Function: erc-tls

Select connection parameters and run ERC over TLS. Non-interactively, it takes the following keyword arguments.

  • server
  • port
  • nick
  • password
  • full-name
  • client-certificate

That is, if called with the following arguments, server and full-name will be set to those values, whereas erc-compute-port and erc-compute-nick will be invoked for the values of the other parameters, and client-certificate will be nil.

(erc-tls :server "irc.libera.chat" :full-name "J. Random Hacker")

To use a certificate with erc-tls, specify the optional client-certificate keyword argument, whose value should be as described in the documentation of open-network-stream: if non-nil, it should either be a list where the first element is the file name of the private key corresponding to a client certificate and the second element is the file name of the client certificate itself to use when connecting over TLS, or t, which means that auth-source will be queried for the private key and the certificate. Authenticating using a TLS client certificate is also referred to as “CertFP” (Certificate Fingerprint) authentication by various IRC networks.

Examples of use:

(erc-tls :server "irc.libera.chat" :port 6697
         :client-certificate
         '("/home/bandali/my-cert.key"
           "/home/bandali/my-cert.crt"))
(erc-tls :server "irc.libera.chat" :port 6697
         :client-certificate
         `(,(expand-file-name "~/cert-libera.key")
           ,(expand-file-name "~/cert-libera.crt")))
(erc-tls :server "irc.libera.chat" :port 6697
         :client-certificate t)

In the case of :client-certificate t, you will need to add a line like the following to your authinfo file (e.g. ~/.authinfo.gpg):

machine irc.libera.chat key /home/bandali/my-cert.key cert /home/bandali/my-cert.crt

See Help for users in Emacs auth-source Library, for more on the .authinfo/.netrc backend of auth-source.

Server

Function: erc-compute-server &optional server

Return an IRC server name.

This tries a number of increasingly more default methods until a non-nil value is found.

  • server (the argument passed to this function)
  • The erc-server option
  • The value of the IRCSERVER environment variable
  • The erc-default-server variable
User Option: erc-server

IRC server to use if one is not provided.

Port

Function: erc-compute-port &optional port

Return a port for an IRC server.

This tries a number of increasingly more default methods until a non-nil value is found.

  • port (the argument passed to this function)
  • The erc-port option
  • The erc-default-port variable
User Option: erc-port

IRC port to use if not specified.

This can be either a string or a number.

Nick

Function: erc-compute-nick &optional nick

Return user’s IRC nick.

This tries a number of increasingly more default methods until a non-nil value is found.

  • nick (the argument passed to this function)
  • The erc-nick option
  • The value of the IRCNICK environment variable
  • The result from the user-login-name function
User Option: erc-nick

Nickname to use if one is not provided.

This can be either a string, or a list of strings. In the latter case, if the first nick in the list is already in use, other nicks are tried in the list order.

User Option: erc-format-nick-function

A function to format a nickname for message display

You can set this to erc-format-@nick to display user mode prefix

(setq erc-format-nick-function 'erc-format-@nick)
User Option: erc-nick-uniquifier

The string to append to the nick if it is already in use.

User Option: erc-try-new-nick-p

If the nickname you chose isn’t available, and this option is non-nil, ERC should automatically attempt to connect with another nickname.

You can manually set another nickname with the /NICK command.

Password

User Option: erc-prompt-for-password

If non-nil (the default), M-x erc prompts for a password.

If you prefer, you can set this option to nil and use the auth-source mechanism to store your password. For instance, if you use ~/.authinfo as your auth-source backend, then put something like the following in that file:

machine irc.example.net login "#fsf" password sEcReT

ERC also consults auth-source to find any channel keys required for the channels that you wish to autojoin, as specified by the variable erc-autojoin-channels-alist.

For more details, see auth-source in Emacs auth-source Library.

Full name

Function: erc-compute-full-name &optional full-name

Return user’s full name.

This tries a number of increasingly more default methods until a non-nil value is found.

  • full-name (the argument passed to this function)
  • The erc-user-full-name option
  • The value of the IRCNAME environment variable
  • The result from the user-full-name function
User Option: erc-user-full-name

User full name.

This can be either a string or a function to call.


5.2 Sample Configuration

Here is an example of configuration settings for ERC. This can go into your Emacs configuration file. Everything after the (require 'erc) command can optionally go into ~/.emacs.d/.ercrc.el.

;;; Sample ERC configuration

;; Load authentication info from an external source.  Put sensitive
;; passwords and the like in here.
(load "~/.emacs.d/.erc-auth")

;; This is an example of how to make a new command.  Type "/uptime" to
;; use it.
(defun erc-cmd-UPTIME (&rest ignore)
  "Display the uptime of the system, as well as some load-related
stuff, to the current ERC buffer."
  (let ((uname-output
         (replace-regexp-in-string
          ", load average: " "] {Load average} ["
          ;; Collapse spaces, remove
          (replace-regexp-in-string
           " +" " "
           ;; Remove beginning and trailing whitespace
           (replace-regexp-in-string
            "^ +\\|[ \n]+$" ""
            (shell-command-to-string "uptime"))))))
    (erc-send-message
     (concat "{Uptime} [" uname-output "]"))))

;; This causes ERC to connect to the Libera.Chat network upon hitting
;; C-c e f.  Replace MYNICK with your IRC nick.
(global-set-key "\C-cef" (lambda () (interactive)
                           (erc :server "irc.libera.chat" :port "6667"
                                :nick "MYNICK")))

;; This causes ERC to connect to the IRC server on your own machine (if
;; you have one) upon hitting C-c e b.  Replace MYNICK with your IRC
;; nick.  Often, people like to run bitlbee (https://bitlbee.org/) as an
;; AIM/Jabber/MSN to IRC gateway, so that they can use ERC to chat with
;; people on those networks.
(global-set-key "\C-ceb" (lambda () (interactive)
                           (erc :server "localhost" :port "6667"
                                :nick "MYNICK")))

;; Make C-c RET (or C-c C-RET) send messages instead of RET.  This has
;; been commented out to avoid confusing new users.
;; (define-key erc-mode-map (kbd "RET") nil)
;; (define-key erc-mode-map (kbd "C-c RET") 'erc-send-current-line)
;; (define-key erc-mode-map (kbd "C-c C-RET") 'erc-send-current-line)

;;; Options

;; Join the #emacs and #erc channels whenever connecting to
;; Libera.Chat.
(setq erc-autojoin-channels-alist
      '(("Libera.Chat" "#emacs" "#erc")))

;; Rename server buffers to reflect the current network name instead
;; of SERVER:PORT (e.g., "Libera.Chat" instead of
;; "irc.libera.chat:6667").  This is useful when using a bouncer like
;; ZNC where you have multiple connections to the same server.
(setq erc-rename-buffers t)

;; Interpret mIRC-style color commands in IRC chats
(setq erc-interpret-mirc-color t)

;; The following are commented out by default, but users of other
;; non-Emacs IRC clients might find them useful.
;; Kill buffers for channels after /part
;; (setq erc-kill-buffer-on-part t)
;; Kill buffers for private queries after quitting the server
;; (setq erc-kill-queries-on-quit t)
;; Kill buffers for server messages after quitting the server
;; (setq erc-kill-server-buffer-on-quit t)

5.3 Options

This section is extremely incomplete. For now, the easiest way to check out all the available options for ERC is to do M-x customize-group RET erc RET.

User Option: erc-hide-list

If non, nil, this is a list of IRC message types to hide, e.g.:

(setq erc-hide-list '("JOIN" "PART" "QUIT"))
User Option: erc-network-hide-list

If non, nil, this is a list of IRC networks and message types to hide, e.g.:

(setq erc-network-hide-list (("Libera.Chat" "JOIN" "PART" "QUIT")
("OFTC" "JOIN" "PART""))
User Option: erc-channel-hide-list

If non, nil, this is a list of IRC channels and message types to hide, e.g.:

(setq erc-channel-hide-list (("#erc" "JOIN" "PART" "QUIT")
("#emacs" "NICK"))
User Option: erc-lurker-hide-list

Like erc-hide-list, but only applies to messages sent by lurkers. The function erc-lurker-p determines whether a given nickname is considered a lurker.

User Option: erc-rename-buffers

If non, nil, this will rename server buffers to reflect the current network name instead of IP:PORT

(setq erc-rename-buffers t)

6 Getting Help and Reporting Bugs

After you have read this guide, if you still have questions about ERC, or if you have bugs to report, there are several places you can go.


7 History

ERC was originally written by Alexander L. Belikoff and Sergey Berezin. They stopped development around December 1999. Their last released version was ERC 2.0.

P.S.: If one of the original developers of ERC reads this, we’d like to receive additional information for this file and hear comments in general.


Appendix A GNU Free Documentation License

Version 1.3, 3 November 2008
Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
https://fsf.org/

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
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    7. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document’s license notice.
    8. Include an unaltered copy of this License.
    9. 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.
    10. 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.
    11. 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.
    12. 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.
    13. Delete any section Entitled “Endorsements”. Such a section may not be included in the Modified Version.
    14. Do not retitle any existing section to be Entitled “Endorsements” or to conflict in title with any Invariant Section.
    15. 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 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.

  6. 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.”

  7. 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.

  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 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.

  9. 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.

  10. 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.

  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 https://www.gnu.org/licenses/.

    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.

  12. 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.

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 1.3
  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''.

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.


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