HOWTO-template for big HOWTOs <!-- insert your title here --> <author>Stein Gjoen, <tt/ <!-- insert your name here --> <date>v0.09, 20 May 2002 <!-- always have a version number and a date --> <abstract> <!-- the abstract: a short and precise description --> <nidx>(your index root)</nidx> <!-- add indexing keywords as you go along --> <!-- nidx means the indexed word is not in output of main text, only in the index --> This is a fully working template for big HOWTOs. The source contains fully described slots to make a convenient framework for you to fill in for making your own HOWTO, suggesting some names, conventions and contents for the chapters. </abstract> <!-- Table of contents --> <toc> <!-- Begin the document --> <sect>Introduction <p> <!-- always use a p tag (paragraph) immediately after a sect tag --> <nidx>(your index root)!introduction</nidx> <!-- here introduction is a sub entry of template, exclamationmark is separator --> <em>My comments to the reader is in this style (emphasized)</em>. Example lines are in plain roman style. <em>Note that extra comments and advice is found in comments within the SGML source.</em> <!-- such as this comment --> For various reasons this brand new release is codenamed the <bf/release/ release. New code names will appear as per industry standard guidelines to emphasize the state-of-the-art-ness of this document. <p> This document was written when I read a feedback asking for a template to fill in to make new HOWTOs. This template is made by extracting the skeletal structure of the Multi Disk HOWTO which is a rather large HOWTO. <em>This Template is a suggestion and a starting point, a check list and examples for authors; it is not a requirement to be followed slavishly. Over time HOWTOs might also outgrow any template since in the end the goal is to inform readers efficiently.</em> Stating the background is a simple way to getting started writing the intro. First of all we need a bit of legalese. Recent development shows it is quite important. <sect1>Copyright <p> <em>Copyright is a source of much and continuous debate on the LDP mailing list. For more in depth information please consult the Manifesto at the </em> <url url="" name="LinuxDoc"> site. <em> The purpose of having a license is to allow appropriate distribution. You can use any license that meets the Manifesto. What follows is a boilerplate licence. </em> This document is Copyright 2000 by John Doe (change to your name). Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 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 can be found in Appendix A. <em>Replace with your name, or supply a new license, when you use this template for a new HOWTO.</em> <!-- Old style copyright removed --> <!-- Copyright (c) 2000 by John Doe (change to your name) <P> Please freely copy and distribute (sell or give away) this document in any format. It's requested that corrections and/or comments be forwarded to the document maintainer. You may create a derivative work and distribute it provided that you: <itemize> <item> Send your derivative work (in the most suitable format such as sgml) to the LDP (Linux Documentation Project) or the like for posting on the Internet. If not the LDP, then let the LDP know where it is available. <item> License the derivative work with this same license or use GPL. Include a copyright notice and at least a pointer to the license used. <item> Give due credit to previous authors and major contributors. </itemize> <P> If you're considering making a derived work other than a translation, it's requested that you discuss your plans with the current maintainer. --> <sect1>Disclaimer <p> Use the information in this document at your own risk. I disavow any potential liability for the contents of this document. Use of the concepts, examples, and/or other content of this document is entirely at your own risk. All copyrights are owned by their owners, unless specifically noted otherwise. Use of a term in this document should not be regarded as affecting the validity of any trademark or service mark. Naming of particular products or brands should not be seen as endorsements. You are strongly recommended to take a backup of your system before major installation and backups at regular intervals. <sect1>News <p> <nidx>(your index root)!news on</nidx> <em>This is where you make a summary of what is new. When a HOWTO exceeds 20 pages it takes more than a casual read to find the updates. This is where you help your readers with that, alerting them to specific and important news.</em> This is the second release featuring more samples and an improved structure. <!-- This is the first release. No news yet. --> <!-- Note that you might wish to keep old news commented out for reference and perhaps state news as latest and next to latest update. --> <em>Tell people where the document home page is so the very newest release could be found in case of problems with the main <url url="" name="Linux Documentation Project"> homepage. </em> The latest version number of this document can be gleaned from my plan entry if you <!-- do "finger" --> <url url="" name="finger"> my Nyx account. <em>If you have the capacity it would be nice to make the HOWTO available in a number of formats.</em> Also, the latest version of the Template will be available on my web space on Nyx in a number of formats: <itemize> <item> <url url="˜sgjoen/template.html" name="HTML">. <item> <url url="˜sgjoen/template.txt" name="plain ASCII text">. <!-- consider PostScript and perhaps also PDF formates <item> <url url="˜sgjoen/" name="compressed postscript US letter format">. <item> <url url="˜sgjoen/" name="compressed postscript European A4 format">. --> <item> <url url="˜sgjoen/template.sgml" name="SGML source">. </itemize> <em>Note that paper sizes vary in the world, A4 and US letter differ significantly.</em> <sect1>Credits <p> <em>It is always nice to acknowledge people who help you with inputs, it is also regarded by many as important in the Linux world new economy</em> In this version I have the pleasure of acknowledging <tscreen><verb> corff (at) ZEDAT.FU-Berlin.DE dwood (at) lcl (at) kgh12351 (at) dave (at) name (at) </verb></tscreen> <em>Scramble the addresses so email harvesters cannot get addresses from your HOWTO and then spam people. That has happened in the past.</em> <sect1>Translations <p> Not everyone speaks English, pointers to translations are nice. Also your translators tend to give very important inputs. <itemize> <item><url url="" name="German Translation"> by <tt/someone (at) <item><url url="" name="Swedish Translation "> by <tt/someone (at) <item><url url="" name="French Translation"> by <tt/someone (at) <item><url url="" name="Chinese Translation"> by <tt/someone (at) <item><url url="" name="Italian Translation"> by <tt/someone (at) </itemize> Also Somecompany is acknowledged for sending me documentation on their gizmos as well as permission to quote from the material. These quotes have been approved before appearing here and will be clearly labelled. Any comments or suggestions can be mailed to my mail address on Nyx: <htmlurl url="" name="">. <p> <!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% --> <sect>Structure <p> <em>A quick overview on how all parts fit together in the structure. Here I use an example from my Multi Disk HOWTO.</em> As this type of document is supposed to be as much for learning as a technical reference document I have rearranged the structure to this end. For the designer of a system it is more useful to have the information presented in terms of the goals of this exercise than from the point of view of the logical layer structure of the devices themselves. Nevertheless this document would not be complete without such a layer structure the computer field is so full of, so I will include it here as an introduction to how it works. <sect1>Logical structure <p> <nidx>(your index root)!structure, I/O subsystem</nidx> This is based on how each layer access each other, traditionally with the application on top and the physical layer on the bottom. It is quite useful to show the interrelationship between each of the layers used in controlling drives. <tscreen><verb> ___________________________________________________________ |__ File structure ( /usr /tmp etc) __| |__ File system (ext2fs, vfat etc) __| |__ Volume management (AFS) __| |__ RAID, concatenation (md) __| |__ Device driver (SCSI, IDE etc) __| |__ Controller (chip, card) __| |__ Connection (cable, network) __| |__ Drive (magnetic, optical etc) __| ----------------------------------------------------------- </verb></tscreen> In the above diagram both volume management and RAID and concatenation are optional layers. The 3 lower layers are in hardware. All parts are discussed at length later on in this document. <sect1>Document structure <p> Most users start out with a given set of hardware and some plans on what they wish to achieve and how big the system should be. This is the point of view I will adopt in this document in presenting the material, starting out with hardware, continuing with design constraints before detailing the design strategy that I have found to work well. I have used this both for my own personal computer at home, a multi purpose server at work and found it worked quite well. In addition my Japanese co-worker in this project have applied the same strategy on a server in an academic setting with similar success. Finally at the end I have detailed some configuration tables for use in your own design. If you have any comments regarding this or notes from your own design work I would like to hear from you so this document can be upgraded. <sect1>Reading plan <p> <em>As you go beyond 50 pages or so there will be a lot of text that experts and even the experienced do not need to read. Keeping in mind that we wish to care for all kinds of people in the Linux world we might have to make a reading plan. Again example follows from my HOWTO.</em> Although not the biggest HOWTO it is nevertheless rather big already and I have been requested to make a reading plan to make it possible to cut down on the volume <descrip> <tag/Expert/ (aka the elite). If you are familiar with Linux as well as disk drive technologies you will find most of what you need in the appendices. Additionally you are recommended to read the FAQ and the <ref id="bits-n-pieces" name="Bits'n'pieces"> chapter. <tag/Experienced/ (aka Competent). If you are familiar with computers in general you can go straight to the chapters on <ref id="technologies" name="technologies"> and continue from there on. <tag/Newbie/ (mostly harmless). You just have to read the whole thing. Sorry. In addition you are also recommended to read all the other disk related HOWTOs. </descrip> <sect>Technologies <label id="technologies"> <p> <nidx>(your index root)!technologies</nidx> <em>Introduction of technology for the newbie with a few references to detailled works. Remember that not everyone has Internet access so you have to explain in sufficient details so even the newbie can get by.</em> <sect>Implementation <p> <nidx>(your index root)!implementation</nidx> <em>Now your readers should have a sufficient knowledge of what this is about and now we come to the hands on of implementing your clever scheme.</em> <sect>Maintenance <p> <nidx>(your index root)!maintenance</nidx> <em>Few systems and designs are maintenance free, here you explain how to keep the system running.</em> <sect>Advanced Issues <p> <nidx>(your index root)!advanced topics</nidx> <em>You can get most things up and running in a quick and dirty fashion, useful for testing and getting used to how things work. For more serious use you would need to be a little more advanced. This is the place to explain it all, if applicable.</em> <sect>Troubleshooting <label id="troubleshooting"> <p> <nidx>(your index root)!troubleshooting</nidx> <em>Many problems can be solved by a simple structured approach, analysing the symptoms, finding the cause and determining the solution. The following is an excerpts from the Multi Disk HOWTO.</em> <sect1>During Installation <sect2>Locating Disks <p> <descrip> <tag/Symptoms/Cannot find disk <tag/Problem/How to find what drive letter corresponds to what disk/partition <tag/Solution/Remember Linux does not use drive letters but device names. More information can be found in section "Drive names". </descrip> <p> <descrip> <tag/Symptoms/Cannot partition disk <tag/Problem/Most likely wrong input to the command line for <tt/fdisk/ or similar tool. <tag/Solution/Remember to use <tt>/dev/hda</tt> rather than just <tt>hda</tt>. Also do not use numbers behind <tt>hda</tt>, those indicate partitions. </descrip> <sect2>Formatting <p> <descrip> <tag/Symptoms/Cannot format disk. <tag/Problem/Strictly speaking you format partitions not disks. <tag/Solution/Make sure you add the partition number after the device name of the disk, for instance <tt>/dev/hda1</tt> to the command line. </descrip> <sect>Further Information <p> <nidx>(your index root)!information resources</nidx> <em>A HOWTO cannot describe everything, some times the user has to venture out on the net to get more information or just updates. Here is the place to tell where and how. Again examples from my HOWTO, replace as needed.</em> There is wealth of information one should go through when setting up a major system, for instance for a news or general Internet service provider. The FAQs in the following groups are useful: <sect1>News groups <p> <nidx>(your index root)!information resources!news groups</nidx> Some of the most interesting news groups are: <itemize> <item><url url="" name="Storage">. <item><url url="" name="PC storage">. <item><url url="news:alt.filesystems.afs" name="AFS">. <item><url url="news:comp.periphs.scsi" name="SCSI">. <item><url url="news:comp.os.linux.setup" name="Linux setup">. </itemize> Most newsgroups have their own FAQ that are designed to answer most of your questions, as the name Frequently Asked Questions indicate. Fresh versions should be posted regularly to the relevant newsgroups. If you cannot find it in your news spool you could go directly to the <url url="" name="FAQ main archive FTP site">. The WWW versions can be browsed at <url url="" name="FAQ main archive WWW site">. Some FAQs have their own home site, of particular interest here are <itemize> <item><url url="˜filipg/HTML/LINK/F_SCSI.html" name="SCSI FAQ"> and <item><url url="˜rdv/comp_arch_storage/FAQ-1.html" name=" FAQ">. </itemize> <sect1>Mailing Lists <p> <nidx>(your index root)!information resources!mailing lists</nidx> These are low noise channels mainly for developers. Think twice before asking questions there as noise delays the development. Some relevant lists are <tt/linux-raid/, <tt/linux-scsi/ and <tt/linux-ext2fs/. Many of the most useful mailing lists run on the <tt></tt> server but this is notoriously overloaded, so try to find a mirror. There are some lists mirrored at <url url="" name="The Redhat Home Page">. Many lists are also accessible at <url url="" name="linuxhq">, and the rest of the web site is a gold mine of useful information. If you want to find out more about the lists available you can send a message with the line <tt/lists/ to the list server at ( <htmlurl url="" name="">). If you need help on how to use the mail server just send the line <tt/help/ to the same address. Due to the popularity of this server it is likely it takes a bit to time before you get a reply or even get messages after you send a <tt/subscribe/ command. There is also a number of other majordomo list servers that can be of interest such as the EATA driver list ( <htmlurl url="" name="">) and the Intelligent IO list <htmlurl url="" name="">. Mailing lists are in a state of flux but you can find links to a number of interesting lists from the <url url="" name="Linux Documentation Homepage">. <sect1>HOWTO <p> <nidx>(your index root)!information resources!HOWTOs</nidx> These are intended as the primary starting points to get the background information as well as show you how to solve a specific problem. Some relevant HOWTOs are <tt/Bootdisk/, <tt/Installation/, <tt/SCSI/ and <tt/UMSDOS/. The main site for these is the <url url="" name="LDP archive"> at Metalab (formerly known as Sunsite). There is a a new HOWTO out that deals with setting up a DPT RAID system, check out the <url url="" name="DPT RAID HOWTO homepage">. <sect1>Mini-HOWTO <p> <nidx>(your index root)!information resources!mini-HOWTOs</nidx> These are the smaller free text relatives to the HOWTOs. Some relevant mini-HOWTOs are <tt/Backup-With-MSDOS/, <tt/Diskless/, <tt/LILO/, <tt/Large Disk/, <tt/Linux+DOS+Win95+OS2/, <tt/Linux+OS2+DOS/, <tt/Linux+Win95/, <tt/NFS-Root/, <tt/Win95+Win+Linux/, <tt/ZIP Drive/ . You can find these at the same place as the HOWTOs, usually in a sub directory called <tt/mini/. Note that these are scheduled to be converted into SGML and become proper HOWTOs in the near future. The old <tt/Linux Large IDE mini-HOWTO/ is no longer valid, instead read <tt>/usr/src/linux/drivers/block/README.ide</tt> or <tt>/usr/src/linux/Documentation/ide.txt</tt>. <sect1>Local Resources <p> <nidx>(your index root)!information resources!local</nidx> In most distributions of Linux there is a document directory installed, have a look in the <htmlurl url="file:///usr/doc" name="/usr/doc"> directory. where most packages store their main documentation and README files etc. Also you will here find the HOWTO archive ( <htmlurl url="file:///usr/doc/HOWTO" name="/usr/doc/HOWTO">) of ready formatted HOWTOs and also the mini-HOWTO archive ( <url url="file:///usr/doc/HOWTO/mini" name="/usr/doc/HOWTO/mini">) of plain text documents. Many of the configuration files mentioned earlier can be found in the <htmlurl url="file:///etc" name="/etc"> directory. In particular you will want to work with the <htmlurl url="file:///etc/fstab" name="/etc/fstab"> file that sets up the mounting of partitions and possibly also <htmlurl url="file:///etc/mdtab" name="/etc/mdtab"> file that is used for the <tt/md/ system to set up RAID. The kernel source in <url url="file:///usr/src/linux" name="/usr/src/linux"> is, of course, the ultimate documentation. In other words, <em>use the source, Luke</em>. It should also be pointed out that the kernel comes not only with source code which is even commented (well, partially at least) but also an informative <url url="file:///usr/src/linux/Documentation" name="documentation directory">. If you are about to ask any questions about the kernel you should read this first, it will save you and many others a lot of time and possibly embarrassment. Also have a look in your system log file ( <htmlurl url="file:///var/log/messages" name="/var/log/messages">) to see what is going on and in particular how the booting went if too much scrolled off your screen. Using <tt>tail -f /var/log/messages</tt> in a separate window or screen will give you a continuous update of what is going on in your system. You can also take advantage of the <htmlurl url="file:///proc" name="/proc"> file system that is a window into the inner workings of your system. Use <tt/cat/ rather than <tt/more/ to view the files as they are reported as being zero length. Reports are that <tt/less/ works well here. <sect1>Web Pages <p> <nidx>(your index root)!information resources!WWW</nidx> <nidx>(your index root)!information resources!web pages</nidx> There is a huge number of informative web pages out there and by their very nature they change quickly so don't be too surprised if these links become quickly outdated. A good starting point is of course the <url url="" name="Linux Documentation Project"> home page, an information central for documentation, project pages and much, much more. Please let me know if you have any other leads that can be of interest. <sect>Getting Help <p> <nidx>(your index root)!assistance, obtaining</nidx> <em>Your reader might still end up in a situation where extra help is needed from someone else, perhaps on the net. In order to get fast and efficient help it is best first to get some details on your system. What details matter depends on type of problem. For disk problems you need to know the disk controllers etc, for networking problems you have to know what ethernet card is used and version of drivers etc. Here is the place to suggest what details to have ready when asking for help.</em> In the end you might find yourself unable to solve your problems and need help from someone else. The most efficient way is either to ask someone local or in your nearest Linux user group, search the web for the nearest one. Another possibility is to ask on Usenet News in one of the many, many newsgroups available. The problem is that these have such a high volume and noise (called low signal-to-noise ratio) that your question can easily fall through unanswered. No matter where you ask it is important to ask well or you will not be taken seriously. Saying just <it/my disk does not work/ is not going to help you and instead the noise level is increased even further and if you are lucky someone will ask you to clarify. Instead describe your problems in some detail that will enable people to help you. The problem could lie somewhere you did not expect. Therefore you are advised to list up the following information on your system: <descrip> <tag/Hardware/ <itemize> <item>Processor <item>DMA <item>IRQ <item>Chip set (LX, BX etc) <item>Bus (ISA, VESA, PCI etc) <item>Expansion cards used (Disk controllers, video, IO etc) </itemize> <tag/Software/ <itemize> <item>BIOS (On motherboard and possibly SCSI host adapters) <item>LILO, if used <item>Linux kernel version as well as possible modifications and patches <item>Kernel parameters, if any <item>Software that shows the error (with version number or date) </itemize> <tag/Peripherals/ <itemize> <item>Type of disk drives with manufacturer name, version and type <item>Other relevant peripherals connected to the same busses </itemize> </descrip> Remember that booting text is logged to <tt>/var/log/messages</tt> which can answer most of the questions above. Obviously if the drives fail you might not be able to get the log saved to disk but you can at least scroll back up the screen using the <tt/SHIFT/ and <tt/PAGE UP/ keys. It may also be useful to include part of this in your request for help but do not go overboard, keep it <em/brief/ as a complete log file dumped to Usenet News is more than a little annoying. <sect>Concluding Remarks <p> <nidx>(your index root)!conclusion</nidx> <em>Just summing up... Also a place for general recommendations.</em> <sect>Questions and Answers <p> <nidx>(your index root)!FAQ</nidx> <nidx>(your index root)!frequently asked questions</nidx> <em>Check the newsgroups and try to determine some frequent problems and cover them here. Again an example from my HOWTO.</em> This is just a collection of what I believe are the most common questions people might have. Give me more feedback and I will turn this section into a proper FAQ. <itemize> <item>Q:How many physical disk drives (spindles) does a Linux system need? <p> A: Linux can run just fine on one drive (spindle). Having enough RAM (around 32 MB, and up to 64 MB) to support swapping is a better price/performance choice than getting a second disk. (E)IDE disk is usually cheaper (but a little slower) than SCSI. <item>Q: Are there any disadvantages in this scheme? <p> A: There is only a minor snag: if even a single partition overflows the system might stop working properly. The severity depends of course on what partition is affected. Still this is not hard to monitor, the command <tt/df/ gives you a good overview of the situation. Also check the swap partition(s) using <tt/free/ to make sure you are not about to run out of virtual memory. <item>Q: OK, so should I split the system into as many partitions as possible for a single drive? <p> A: No, there are several disadvantages to that. First of all maintenance becomes needlessly complex and you gain very little in this. In fact if your partitions are too big you will seek across larger areas than needed. This is a balance and dependent on the number of physical drives you have. </itemize> <em>(rest deleted.)</em> <sect>Bits and Pieces <label id="bits-n-pieces"> <p> <nidx>(your index root)!miscellaneous</nidx> <em>This is basically a section where I stuff all the bits I have not yet decided where should go, yet that I feel is worth knowing about. It is a kind of transient area.</em> <sect>Examples <p> <nidx>(your index root)!examples</nidx> <em>Example designs and sample configuration files and other relevant details is always handy. Keep large samples at the end to avoid breaking the flow of the HOWTO reading. Small samples are useful within the main body of the HOWTO.</em> <sect>Samples <label id="samples"> <p> <em>This section gives some simple SGML examples you could copy. Read the source to see how it was done.</em> <!-- you can also have comments in the SGML source --> <sect1>Lists <p> <em>Lists appears many times, in a number of formats:</em> <p> Unlisted bullets: <p> <itemize> <item>Apples <item>Oranges <item>Bananas </itemize> <p> Tagged lists <p> <descrip> <tag/Fruits/ such as apples, oranges, and more. <tag/Nuts/ Don't eat too many; you are what you eat. <tag/Vegetables/ Potatos are spelled with care. </descrip> <sect1>Links <p> <em>Links can be used within your documents to refer to different sections and chapters or to refer to documents external to yours.</em> <p> Internal links <p> Click on <ref id="samples" name="this"> link to jump to the top of this chapter. Note the anchor at the section tag. <p> External links <p> Click on <url url="" name="this"> link to jump to the LDP site. Note you can use http, ftp, news and other protocols in the locator if required. Note that the character ˜ has to be escaped, see the source for details. <!-- ˜ is the way of writing the tilde character --> <sect1>Images <p> <em>Avoid diagrams if possible as this cannot be rendered in the ascii outputs which are still needed by many around the world.</em> <figure loc="tbp"> <eps file="somegraphics.eps"> <img src="somegraphics.jpg"> <caption>Graphics Test Image</caption> </figure> <!-- <img file="/usr/src/linux/logo.gif"> --> <sect>Table Samples <label id="tblsamples"> <p> <em>This section gives an example of writing a table.</em> <table loc=p> <tabular ca="rll"> Line No.<colsep>Country <colsep>Capital <rowsep><hline> 1 <colsep>Norway <colsep>Oslo <rowsep> 2 <colsep>Japan <colsep>Tokyo <rowsep> 3 <colsep>Finland <colsep>Helsinki <rowsep> </tabular> <caption>Some capitals</caption> </table> <sect>Notes on Style <label id="style"> <p> <em> Not much here yet but I would like to suggest a few points. </em> <descrip> <tag/Tags/ Try to use tags extensively <tag/Types/ Try using functional tags such as em rather than it. <tag/Files/ Try using functional links to files such as <tt><htmlurl url="file:///usr/doc" name="/usr/doc"></tt> rather than just /usr/doc. <tag/Commands/ Try to refer to man pages including section number <tt>df (1)</tt> rather than just df. </descrip> <sect>Converting the SGML File <p> Having made the SGML file we are now ready to convert it to the various output formats we need. The following is my script to process my Multi Disk HOWTO: <code> sgml2txt -f disk.sgml sgml2html disk.sgml sgml2latex --papersize=a4 --language=english --output=ps ~stein/doc/disk.sgml mv gzip -9 sgml2latex --papersize=letter --language=english --output=ps ~stein/doc/disk.sgml mv gzip -9 </code> The template can be converted as is, substitute "disk.sgml" with the filename of this template to see what it looks like. If your document is small (such as this template) you might find it more convenient to keep formatted versions in one single file rather than splitting it for every chapter: <code> sgml2html --split=0 template.sgml </code> <sect>Appendix A: Copyright <p> <tscreen><verb> GNU Free Documentation License Version 1.1, March 2000 Copyright (C) 2000 Free Software Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. 0. PREAMBLE The purpose of this License is to make a manual, textbook, or other written document "free" in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others. This License is a kind of "copyleft", which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for 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 that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. The "Document", below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as "you". A "Modified Version" of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language. A "Secondary Section" is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document's overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (For example, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them. The "Invariant Sections" are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. The "Cover Texts" are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A "Transparent" copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, whose contents can be viewed and edited directly and straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup has been designed to thwart or discourage subsequent modification by readers is not Transparent. A copy that is not "Transparent" is called "Opaque". Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML designed for human modification. Opaque formats include PostScript, PDF, proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML produced by some word processors for output purposes only. The "Title Page" means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, "Title Page" means the text near the most prominent appearance of the work's title, preceding the beginning of the body of the text. 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 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 publicly-accessible computer-network location containing a complete Transparent copy of the Document, free of added material, which the general network-using public has access to download anonymously at no charge using public-standard network protocols. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public. It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document. 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 less than five). C. State on the Title page the name of the publisher of the Modified Version, as the publisher. D. Preserve all the copyright notices of the Document. E. Add an appropriate copyright notice for your modifications adjacent to the other copyright notices. F. Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below. G. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document's license notice. H. Include an unaltered copy of this License. I. Preserve the section entitled "History", and its title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section entitled "History" in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous 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. In any section entitled "Acknowledgements" or "Dedications", preserve the section's title, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications 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 as "Endorsements" or to conflict in title with any Invariant Section. If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version's license notice. These titles must be distinct from any other section titles. You may add a section entitled "Endorsements", provided it contains nothing but endorsements of your Modified Version by various parties--for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard. You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one. The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version. 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. 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, does not as a whole count as a Modified Version of the Document, provided no compilation copyright is claimed for the compilation. Such a compilation is called an "aggregate", and this License does not apply to the other self-contained works thus compiled with the Document, on account of their being thus compiled, if they are not themselves derivative works of the Document. If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one quarter of the entire aggregate, the Document's Cover Texts may be placed on covers that surround only the Document within the aggregate. Otherwise they must appear on covers around the whole aggregate. 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 provided that you also include the original English version of this License. In case of a disagreement between the translation and the original English version of this License, the original English version will prevail. 9. TERMINATION You may not copy, modify, sublicense, or distribute the Document except as expressly provided for under this License. Any other attempt to copy, modify, sublicense or distribute the Document is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance. 10. FUTURE REVISIONS OF THIS LICENSE The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See 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. 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 1.1 or any later version published by the Free Software Foundation; with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. A copy of the license is included in the section entitled "GNU Free Documentation License". If you have no Invariant Sections, write "with no Invariant Sections" instead of saying which ones are invariant. If you have no Front-Cover Texts, write "no Front-Cover Texts" instead of "Front-Cover Texts being LIST"; likewise for Back-Cover Texts. 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. </verb></tscreen> </article>