Copyright © 2020 Cem Keylan

     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 no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License."

Carbs Linux User Manual
***********************

This is the full documentation of Carbs Linux (https://carbslinux.org), from the details of the distribution, installation, to the package manager. It is not yet complete.

You can build and install the info package in order to view this documentation with the info reader. It is divided into sections and easier to read.

Installation
************

These are the step-by-step instructions for installing Carbs Linux. It can be acquired as plain-text to be viewed offline with a pager from https://carbslinux.org/install.txt.

     curl -sL https://carbslinux.org/install.txt | less

Preparing Environment
=====================

To install Carbs Linux, you will need a Live Linux ISO. For that purpose, you can obtain a Gentoo or Void Linux live image. You can follow their instructions to boot and setup your network.

You will need the following programs in order to install Carbs Linux:

  * tar

  * wget

  * xz

  * some form of base utilities (coreutils, sbase, busybox, etc.)

Rest of these instructions will assume that you have set all of these up, and will continue on that point.

Download
--------

First, we need to download the rootfs tarball. You can do the following in order to obtain the rootfs. If you are using an i686 machine, replace the x86_64 with i686. We are setting this in a URL variable so that we don't have to write it every time.

     URL=https://dl.carbslinux.org/releases/x86_64
     wget $URL/carbs-rootfs.tar.xz.sha256
     sha256sum -c carbs-rootfs.tar.xz.sha256

Signature verification
----------------------

It is highly recommended to verify the signature of the tarball. You will need the OpenBSD tool signify(1) for this. Many distributions provide a package for it, if you are using a Carbs Linux host, you can also install the package otools which provides signify. Download the signature first.

     wget $URL/carbs-rootfs.tar.xz.sig

The signature file should say something similar to

     untrusted comment: verify with carbslinux-2021.04.pub
     RWTBBPDVQ+aHB3dme2Kerf8XY+vWkIISp7Za2ufKghtlnRXPyObAQQyvEJYrwMVTaCBlPEnSWcnHQz8Nka06YVOIeextNKZY3AQ=

Grab the key (which probably should be the latest one) that is written on the file from https://dl.carbslinux.org/keys/ so you can verify the signature. The latest Signify public key is also available on the package repository (https://git.carbslinux.org/repository), so you can check the validity of the public key from multiple locations, or just copy paste that portion to a file and use that instead.

     PUBKEY=carbslinux-2021.04.pub
     wget https://dl.carbslinux.org/keys/$PUBKEY

You can now verify the distribution tarball with signify.

     signify -V -m carbs-rootfs.tar.xz -p $PUBKEY

If everything went alright, this should output:

     Signature Verified

Extracting the tarball
----------------------

You will need to extract the tarball to your desired location. For partitioning, you can follow this guide (https://wiki.archlinux.org/index.php/Partitioning). This will assume that you will be mounting your root partition to /mnt.

     mount /dev/sdx1 /mnt
     tar xf carbs-rootfs.tar.xz -C /mnt

Obtain the chroot helper
------------------------

You can obtain the cpt-chroot script in order to do a simple chroot into your new root filesystem.

     wget https://dl.carbslinux.org/distfiles/cpt-chroot
     chmod a+x cpt-chroot

Chroot
======

Chroot into Carbs Linux!

     ./cpt-chroot /mnt

Setting up repositories
-----------------------

Newest tarballs do not come with repositories, so you will need to manually obtain them, and set your CPT_PATH environment variable. Carbs Linux repositories can either be obtained by git or rsync. While rsync repositories are overall faster and smaller, git offers the whole history of the repository and a means to manipulate your repository as you like it. If you want to obtain the git repository, you will need to install git itself.

The following guide will assume that you put the repositories into ~/repos/ directory, but you can put the repositories into any directory you want. So go ahead and create that directory:

     mkdir -p $HOME/repos

 1. Obtaining from git

     Carbs Linux git repositories can be found both from the main server and GitHub (mirror). Here are both their repository links. You can clone any of them.

       * git://git.carbslinux.org/repository

       * https://github.com/carbslinux/repository

          git clone git://git.carbslinux.org/repository $HOME/repos/carbs

 2. Obtaining from rsync

     Carbs Linux rsync repositories live in rsync://carbslinux.org/repo. In order to obtain it, run the following:

          rsync -avc rsync://carbslinux.org/repo $HOME/repos/carbs

 3. Making the package manager use the repositories

     In your shell's configuration file, or in your ~/.profile file, add the following lines:

          CPT_PATH=$HOME/repos/carbs/core
          CPT_PATH=$CPT_PATH:$HOME/repos/carbs/extra
          CPT_PATH=$CPT_PATH:$HOME/repos/carbs/xorg
          CPT_PATH=$CPT_PATH:$HOME/repos/carbs/community
          export CPT_PATH

Updating packages
-----------------

It is good practice to make sure your system is up to date, especially before building new packages. If there is an update for the package manager you will need to update twice.

     cpt-update && cpt-update

Installing packages
-------------------

Since you are operating on a really small base, you might need to build and install new programs to extend the functionality of your system. In order to build and install packages new packages in Carbs, you need to execute the following. "Package" is not actually a package and is given as an example.

     cpt-build   package
     cpt-install package

Essential Software
------------------

Here is a small list of software that you might want to have on your system as you are setting up. You might want to check the Software section in the full documentation to learn more about other packaged software.

BOOTLOADERS

  * efibootmgr

  * grub

FILESYSTEMS

  * e2fsprogs

  * dosfstools

  * ntfs-3g

NETWORKING

  * dhcpcd

  * wpa_supplicant

TEXT EDITORS

  * nano

  * vim

DOCUMENTATION

  * carbs-docs

  * man-pages

  * man-pages-posix

Obtaining the documentation
---------------------------

All the documentation for Carbs Linux can be found on a single info manual to be viewed offline. You can obtain either texinfo or the info packages in order to view the documentation.

     # Install the documentation.
     cpt b carbs-docs && cpt i carbs-docs

     # Install either texinfo or the info package. We will be installing standalone info
     # as it doesn't need perl.
     cpt b info && cpt i info

     # You can then run info and navigate through the documentation.
     info carbslinux

System Configuration
====================

After you have finished installing some extra packages, you can configure your system to your liking.

Configuring hostname
--------------------

You might want to add a hostname, especially in a networked environment. Your hostname will default to 'carbslinux' unless you set this.

     echo your-hostname > /etc/hostname

Hosts file
----------

You can edit your /etc/hosts file, which is the static lookup table for host names. By default, there are two entries for localhost which are OKAY. You can replace the 'localhost' part of these entries to your hostname.

     127.0.0.1  localhost.localdomain localhost
     ::1        localhost.localdomain localhost ip6-localhost

Kernel
======

Kernel isn't managed under the main repositories, even though you could package one for your personal use. Here is an example kernel package (https://github.com/cemkeylan/kiss-repository/tree/master/personal/linux), which you will need to reconfigure for your specific setup if you want to make use of it.

Obtaining the kernel sources
----------------------------

You can visit the https://kernel.org website to choose a kernel that you want to install. Though only the latest stable and longterm (LTS) versions are supported.

     # Download the kernel and extract it
     wget https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.9.1.tar.xz
     tar xf linux-5.9.1.tar.xz

     # Change directory into the kernel sources
     cd linux-5.9.1

Kernel dependencies
-------------------

In order to compile the kernel you will need to install some dependencies. You will need libelf, and bison to compile the kernel. If you want to configure using the menu interface you will also need ncurses.

     # The package manager asks to install if you are building more than one package,
     # so no need to run 'cpt i ...'
     cpt b libelf ncurses

In the vanilla kernel sources, you need perl to compile the kernel, but it can be easily patched out. You will need to apply the following patch. Patch was written by E5ten (https://github.com/E5ten). You will need to obtain and apply the patch in the kernel source directory.

     wget https://dl.carbslinux.org/distfiles/kernel-no-perl.patch
     patch -p1 < kernel-no-perl.patch

Building the kernel
-------------------

Next step is configuring and building the kernel. You can check Gentoo's kernel configuration guide (https://wiki.gentoo.org/wiki/Kernel/Configuration) to learn more about the matter. Overall, Gentoo Wiki is a good place to learn about configuration according to your hardware. The following will assume a monolithic kernel.

     make menuconfig
     make
     install -Dm755 $(make -s image_name) /boot/vmlinuz-linux

Making your system bootable
===========================

In order to be able to boot your fresh system, wou will need an init-daemon, init-scripts and a bootloader. The init daemon is already provided by busybox, but you can optionally change it.

Bootloader
----------

In the main repository, there is efibootmgr and grub to serve as bootloaders. efibootmgr can be used as a standalone bootloader, or can be used to install grub in a UEFI environment. efibootmgr is needed unless you are using a device without UEFI support (or you really want to use BIOS for a reason).

 1. GRUB BIOS installation

          cpt b grub && cpt i grub
          grub-install --target=i386-pc /dev/sdX
          grub-mkconfig -o /boot/grub/grub.cfg

 2. GRUB UEFI installation

          cpt b efibootmgr && cpt i efibootmgr
          cpt b grub && cpt i grub

          grub-install --target=x86_64-efi \
                       --efi-directory=esp \
                       --bootloader-id=CarbsLinux

          grub-mkconfig -o /boot/grub/grub.cfg

Init scripts
------------

Only thing left to do is installing the init-scripts, and now you are almost ready to boot your system!

     cpt b carbs-init && cpt i carbs-init

Fstab
-----

You can now manually edit your fstab entry, or you can use the genfstab tool. If you want to use the tool, exit the chroot and run the following:

     wget https://github.com/cemkeylan/genfstab/raw/master/genfstab
     chmod +x genfstab
     ./genfstab -U /mnt >> /mnt/etc/fstab

Post-installation
=================

The base installation is now complete, you can now fine tune your system according to your needs. Rest of these instructions are completely optional. You can check the rest of the documentation to learn more about the system.

KISS repositories
-----------------

There have been recent changes to the kiss package manager that breaks compatibility with cpt. These changes throw away the entire premise of their "static" packaging system. cpt will never implement those changes, so don't expect any KISS package that was changed during or after July 2021 to work with cpt.

Software
********

The distribution aims to package essential and useful software needed in a practical system. If the repository lacks a package that you use, you may also easily package it yourself or request it to be added to the default repositories over on the IRC channel (#carbslinux on Libera (https://libera.chat)).

This section goes over the details of some packaged software

Init System
===========

Carbs Linux init scripts are run by the init daemon (busybox by default) on boot and shutdown processes. It also provides its own halting program named shalt. This provides a portable method that doesn't rely on non-POSIX external programs.

Configuring Init
----------------

There are three ways you can change the behaviour of the init system. Those are:

  * Kernel Command Line

  * /etc/init/rc.conf file

  * Init Hooks

 1. Kernel Command Line

     On GRUB, you can edit the kernel command line parameters, which will be parsed as variables on the init system. Not all of the parameters will be acted upon, but all of them will be set as variables on the init script. For example an example command line, and how it is interpreted.

          BOOT_IMAGE=/boot/vmlinuz root=/dev/sda2 rw loglevel=3 quiet

     This command line will be parsed to set the following variables:

          BOOT_IMAGE=/boot/vmlinuz
          root=/dev/sda2
          rw=1
          loglevel=3
          quiet=1

     Some of these variables, such as rw=/=ro, loglevel, and quiet, will be used by the init system to change the behaviour of the startup.

 2. /etc/init/rc.conf file

     However, the kernel command line isn't the only place to set your boot parameters. You can specify variables here as well, although note that the kernel command line always gets the priority for these variables since they can be set just before boot.

 3. Init Hooks

     Init hooks are for custom personal commands that the user may want to add to alter their boot. These can be used to load kernel modules, modify interfaces, and lot more. Those hooks are added to the /etc/init directory with the hook name as the suffix. For example, a boot script will be placed as /etc/init/my-hook.boot. Currently, there are 4 hooks that the user can use.

     early-boot
          Run after pseudo-filesystems are mounted.

     boot
          Run before the boot stage is completed.

     pre.shutdown
          Run first when shutting down.

     umount
          Run just before filesystems are unmounted.

     post.shutdown
          Run just before the system is halted.

Changing Init Program
---------------------

By default, Carbs Linux comes preinstalled with busybox-init, but this can easily be replaced without any issues. Currently, available init systems are:

  * sinit

  * busybox init

  * runit

  * shinit

This example is for runit, but it will work with all init systems packaged in the distribution repositories. See the cpt-alternatives(1) manual page for more details.

     cpt a runit /usr/bin/init
     cpt a runit /usr/bin/poweroff
     cpt a runit /usr/bin/reboot

 1. Rebooting after changing init

     After switching init systems, your running init system may not accept the new poweroff commands. You will need to reboot/poweroff using the running init's utilities for the new utilities to work. These commands are for the init system currently running on your system and not the one you are switching to.

     Program
     Command
     busybox
     busybox reboot
     runit
     runit-init 6
     shinit/sinit
     kill -s INT 1

TODO Display Systems
====================

Carbs Linux supports both Xorg and Wayland in the distribution repositories. This section serves as a guide to set up your preferred display server. Follow the subsection for the display server you want to setup.

Wayland
-------

Wayland is a modern display server protocol intended as a replacement for Xorg. Wayland has a much simpler architecture compared to X by its careful design and implementation. Users who want to use a Wayland compositor should follow this section.

 1. Enabling the Wayland repository

     The wayland repository requires packages from xorg and extra repositories. So you should set your $CPT_PATH so that core and extra repositories precede the wayland repository, and the xorg repository should come after wayland. Here is an example below, where $REPOSITORY points to the root of your repository.

          CPT_PATH=$REPOSITORY/core
          CPT_PATH=$CPT_PATH:$REPOSITORY/extra
          CPT_PATH=$CPT_PATH:$REPOSITORY/wayland
          CPT_PATH=$CPT_PATH:$REPOSITORY/xorg
          export CPT_PATH

     After you have enabled your repositories, go ahead and install wayland and wayland-protocols packages.

          cpt-build wayland wayland-protocols

 2. Switching from Xorg

     If you are already an Xorg user, you will need to rebuild some packages so that they support wayland. If you don't have an xorg system, feel free to skip this step. The packages that need a rebuild are:

       * gtk+3

       * gtk4

       * mesa

       * xorg-server (for Xwayland support)

       * webkit2gtk

 3. TODO Installing a Compositor

     The wayland repository currently only contains sway as a Wayland compositor, but you can package something else for your own.

Contribution Guidelines
***********************

Thanks for taking your time to contribute! To maintain stylistic behaviour throughout the repositories, one must adhere to these conventions. Exceptions and changes may occur with good reasoning.

Conventions
===========

[0010]
     Try to keep the file readable.

     [0011]
          Characters on a line shouldn't exceed 100 characters.

     [0012]
          Make sure you don't have code commented out during commit. Uncomment them or remove them completely.

     [0013]
          Do not add comments following the code, add them to the top of the code. It makes it harder to read, and lines longer. Here is an example:

          # Good way of commenting.
          your code goes here

          your code goes here  # Avoid this way of commenting.

Shell Conventions
-----------------

Shell is central to Carbs Linux projects. Most of the tools and packages are written in POSIX sh.

[1010]
     Use 4 spaces for indentation, don't use tabs.

[1020]
     Make sure you don't use bash-specific code.

[1030]
     Make sure you lint your code with shellcheck and if you are new to POSIX sh, use checkbashisms.

[1040]
     Don't spawn new processes if you don't absolutely need to, especially during string manipulation.

     [1041]
          Never use a program for text manupilation that isn't defined in the POSIX standard. This includes gawk and perl.

     [1042]
          Instead of $(basename $file), use ${file##*}.

     [1043]
          Instead of $(dirname $file), use ${file%/*}.

          # This is the same thing as basename /path/to/test.asc .asc

          $ file=/path/to/test.asc file=${file##*/} file=${file%.asc}
          $ echo $file
          test

[1050]
     Instead of backticks, use $(..).

Repository Conventions
----------------------

Repository conventions are important in order to ensure every package resemble themselves. Here are the things to keep in mind:

[2010]
     Prefer tarballs over git packages unless there is a sensible reason. Here are some:

       * Every patch is a new release. (See vim (https://github.com/vim/vim))

       * There are no releases. (See sbase (https://git.suckless.org/sbase))

       * Following a development branch.

       * There has been a long time since the latest release, but upstream is far ahead.

[2020]
     Prefer sources without a dependency to automake. There are usually distribution tarballs that are autoconf'ed. Don't submit tarballs with an automake dependency unless you are sure there is no alternative.

[2030]
     Avoid these packages:

     dbus
          Usually can be disabled by --disable-dbus.

     gettext
          Usually can be disabled by --disable-nls.

[2040]

       * Always install a package to the /usr prefix.

       * All binaries should go to /usr/bin, not /usr/sbin or any other directory.

       * All libraries should go to /usr/lib.

[2050]
     All build files on the repository should be a POSIX shell script, and must start with #!/bin/sh -e.

The next section is about package templates that should be used in order to ensure stylistic consistency. Note that the option configurations shouldn't be taken literally, they are meant as examples.

 1. Make [2210]

          #!/bin/sh -e

          make
          make DESTDIR="$1" PREFIX=/usr install

 2. Configure/Make [2211]

          #!/bin/sh -e

          ./configure \
              --prefix=/usr \
              --disable-option \
              --enable-option

          make
          make DESTDIR="$1" install

 3. Autoconf/Automake [2212]

     See 2020

          #!/bin/sh -e

          autoreconf -fi

          ./configure \
              --prefix=/usr \
              --disable-option \
              --enable-option

          make
          make DESTDIR="$1" install

 4. Meson [2220]

          #!/bin/sh -e

          export DESTDIR=$1

          meson \
              --prefix=/usr \
              -Doption=false \
              -Doption2=true \
              . output

          ninja -C output
          ninja -C output install

 5. Cmake [2230]

          #!/bin/sh -e

          export DESTDIR=$1

          cmake -B build \
              -DCMAKE_INSTALL_PREFIX=/usr \
              -DCMAKE_BUILD_TYPE=Release \
              -DOPTION=ON

          cmake --build   build
          cmake --install build

 6. Go [2240]

          #!/bin/sh -e

          export GOPATH=$PWD/gopath
          trap "go clean -modcache" EXIT INT
          go mod vendor

          go build
          install -Dm755 program "$1/usr/bin/program"

 7. Python [2241]

          #!/bin/sh -e

          python setup.py build
          python setup.py install --prefix=/usr --root="$1"

GNU Free Documentation License
******************************

Version 1.3, 3 November 2008

     Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
     http://fsf.org/

     Everyone is permitted to copy and distribute verbatim copies
     of this license document, but changing it is not allowed.

 0. PREAMBLE

     The purpose of this License is to make a manual, textbook, or other functional and useful document free in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.

     This License is a kind of "copyleft", which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.

     We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does.  But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book.  We recommend this License principally for works whose purpose is instruction or reference.

 1. 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.

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     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.

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     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.

 2. 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.

 3. 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.

 4. 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:

      A. Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission.

      B. List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has fewer than five), unless they release you from this requirement.

      C. State on the Title page the name of the publisher of the Modified Version, as the publisher.

      D. Preserve all the copyright notices of the Document.

      E. Add an appropriate copyright notice for your modifications adjacent to the other copyright notices.

      F. Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below.

      G. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document's license notice.

      H. Include an unaltered copy of this License.

      I. Preserve the section Entitled "History", Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section Entitled "History" in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence.

      J. Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the "History" section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission.

      K. For any section Entitled "Acknowledgements" or "Dedications", Preserve the Title of the section, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein.

      L. Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles.

      M. Delete any section Entitled "Endorsements". Such a section may not be included in the Modified Version.

      N. Do not retitle any existing section to be Entitled "Endorsements" or to conflict in title with any Invariant 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 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.

 5. 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."

 6. COLLECTIONS OF DOCUMENTS

     You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects.

     You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.

 7. AGGREGATION WITH INDEPENDENT WORKS

     A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, 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.

 8. 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.

 9. 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.

 10. FUTURE REVISIONS OF THIS LICENSE

     The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time.  Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.  See http://www.gnu.org/copyleft/.

     Each version of the License is given a distinguishing version number.  If the Document specifies that a particular numbered version of this License "or any later version" applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation.  If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation.  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.

 11. 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.