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LDP Author GuideJorge GodoyEmma Jane HogbinMark F. KomarinskiDavid C. Merrilldavid -AT- lupercalia.net 2005-03-04
This guide describes the process of submitting and publishing a document with The Linux Documentation Project (TLDP). It includes information about the tools, toolchains and formats used by TLDP. The document's primary audience is new TLDP authors, but it also contains information for seasoned documentation authors.
Chapter 1. About this Guide1.1. About this GuideThis document was started on Aug 26, 1999 by Mark F. Komarinski after two day's worth of frustration getting tools to work. If even one LDP author is helped by this, then I did my job. Version 4 of this document was released in early 2004 by Emma Jane Hogbin. A complete overhaul of the document was done to separate the authoring HOWTOs from the technical HOWTOs. The review took approximately eight months. The newest version of this document can be found at the LDP homepage http://www.tldp.org. The original DocBook, HTML, and other formats can be found there. There are many ways to contribute to the Linux movement that do not require the ability to produce software. One such way is to write documentation. The availability of easy-to-understand, technically accurate documentation can make a world of difference to someone who is struggling with Linux software. This Guide is designed to help you research and write a HOWTO which can be submitted to the LDP. The appendices also include sample templates, markup tips and information on how to transform your document from DocBook to another format (such as HTML) for easier proofreading. 1.2. About The LDPThe Linux Documentation Project (LDP) was started to provide new users a way of quickly getting information about a particular subject. It not only contains a series of books on administration, networking, and programming, but also has a large number of smaller works on individual subjects, written by those who have used it. If you want to find out about printing, you get the Printing HOWTO. If you want to do find out if your Ethernet card works with Linux, grab the Ethernet HOWTO, and so on. The LDP provides documents to the world in a variety of convenient formats and also accepts submissions in a number of formats. The current standard for storing the source documentation is a format known as DocBook, see Section 5.2.
The human readable version goes more like this: The LDP consists of a large group of volunteers who are working on documentation about Linux and the programs which run on the Linux kernel. These documents exist primarily as shorter HOWTOs and longer Guides. Both are available from http://www.tldp.org/. This Guide focuses primarily on how to write your own HOWTOs for submission to the LDP. 1.3. FeedbackSend feedback to <discuss@en.tldp.org>. Please reference the title of this document in your email. Please note: you must be subscribed in order to send email to the list. 1.4. Copyrights and TrademarksCopyright 1999-2002 Mark F. Komarinski, David C. Merrill, Jorge Godoy 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, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the appendix entitled "GNU Free Documentation License." 1.5. Acknowledgments and Thanks1.5.1. Version 1 - Version 3Thanks to everyone that gave comments as I was writing this. This includes David Lawyer, Deb Richardson, Daniel Barlow, Greg Ferguson, Mark Craig and other members of the <discuss@en.tldp.org> list. Some sections I got from the HOWTO Index and the sgmltools documentation. The sections on network access to CVS was partially written by Sergiusz Pawlowicz (<ser@metalab.unc.edu>). Sections on DocBook were written by Jorge Godoy (<godoy@conectiva.com>). A great deal of thanks to both of them for their help. 1.5.2. Version 4Thanks to Tabatha Marshall and Machtelt Garrels (Tille) for making sure I actually finished the document. Thanks to my reviewers: Charles Curley, Martin Brown and Tille; and to Saqib Ali for his on-line transformation and validation tools. I have also incorporated a number of useful emails from the LDP mailing lists. The original authors are credited within the document. Special personal thank yous are extended to Steve Champeon for getting me interested in markup languages and for being a wonderful mentor; and to my partner, Graig Kent, for being outrageously supportive. [EJH] 1.6. Document ConventionsThis document uses the following conventions[1]:
Chapter 2. Authoring TLDP Documents: An Introduction2.1. Summary of The LDP ProcessThe following section outlines the process of creating and/or maintaining a document for the Linux Documentation Project. This section includes all steps--some of which may not be relevant to your specific document.
2.2. Mailing ListsYou can subscribe to the following mailing lists:
You can subscribe to either list by sending a request message to either <discuss-subscribe@en.tldp.org> or <docbook-subscribe@en.tldp.org>. The subject of your message should read "subscribe" (no quotes). To remove yourself from the list, send an E-mail with the subject of "unsubscribe" to <discuss-unsubscribe@en.tldp.org> or <docbook-unsubscribe@en.tldp.org>. If you are interested in DocBook beyond the simple markup of your LDP document, you may want to consider joining one of the OASIS DocBook mailing lists. Please see http://docbook.org/mailinglist/index.html for more information. Chapter 3. Writing Your Proposal3.1. Choosing a SubjectIt is likely that if you are reading the Author Guide, you already have a subject in mind. The idea may have come from your own frustrations in trying to get something to work; or maybe you are already writing or have written documentation for other purposes and you want to submit it to the LDP. For example, if you posted a question to a mailing list and it took many posts to resolve the problem -- that might be an incentive to write documentation. Regardless of how you picked your subject, it is important that the LDP community understand why your documentation should be included in its collection. If someone has requested documentation, or you worked with a mailing list to resolve a problem you should include the details in your proposal to the LDP discuss mailing list. It may help others to understand the need for your specific document. 3.2. Scope of Your DocumentNow that you've got a subject, you will need to decide the scope of the document. The scope or subject area should be:
3.2.1. Documentation TemplatesAfter you've decided the scope of your document you should start to consider the type of document that you will write. There are a number of different LDP documentation templates: Guides, HOWTOs, man pages and FAQs. Rahul Sundaram describes their scope in the Linux Documentation Project (LDP) FAQ. Here is a brief overview of what they are with pointers on how you can get started writing your own:
3.3. Unmaintained and Out-of-date DocumentsIf you wish to become the "owner" for an unmaintained document there are several steps you must go through.
3.4. Developing an OutlineBefore you actually begin writing, prepare an outline. An outline will help you to get a clear picture of the subject matter and allow you to concentrate on one small part of the HOWTO at a time. Unless your HOWTO is exceptionally small, your outline will probably be multilevel. When developing a multilevel outline, the top level should contain general subject areas, and sub-headings should be more detailed and specific. Look at each level of your outline independently, and make sure it covers all key areas of the subject matter. Sub-headings should cover all key areas of the heading under which they fall. Each item in your outline should follow the item before it, and lead into the item that comes next. For example, a HOWTO about a particular program shouldn't have a section on configuration before one on installation. You may choose to use the following outline for a HOWTO about using a specific program:
You may find it helpful to try a little "card sorting" at this stage of the writing process. Write all of your mini subject areas onto pieces of paper. Now sort these pieces of paper into main headings and their sub-sections. It may help to shuffle the slips of paper before you start. This will help to give you a fresh set of eyes while working. When you are comfortable with your outline, look it over once more, with a critical eye. Have you covered every relevant topic in sufficient detail? Have you not wandered beyond the scope of the document? It is a good idea to show your outline to others (including The LDP discuss list) to get some feedback. Remember: it is much easier to reorganize your document at the outline stage than doing this after writing it.
3.5. ResearchWhile you are working on your outline you will most likely research your topic--especially to confirm the document you are about to write does not yet exist! Here are a few pointers that will keep you from pulling out your hair later:
Chapter 4. Write4.1. Writing the TextBy now you should have organized your document; you collected bits of raw information and inserted them into the outline. Your next challenge is to massage all of the raw data you've collected into a readable, entertaining and understandable whole. If you are working from an existing document make sure any new pieces of information are in the best possible places. It has taken quite a bit of work to get to the point where you can actually start writing, hasn't it? Well, the hard work begins to pay off for you now. At this stage, you can begin to really use your imagination and creativity to communicate this heap of information. Don't be too clever though! Your readers are already struggling with new concepts--do not make them struggle to understand your language as well. There are a number of classic guides to writing--many of which are available on-line. Their language will seem old, but the messages are still valuable to authors today. These are listed in . Also listed in the resources section are a variety of sites that have information specific to technical writing. The Author Guide wouldn't be complete without mentioning the Plain Language movement. Although directed at simplifying government documents, Writing user-friendly documents is quite useful. It includes before and after writing samples. There's also a PlainTrain writing tutorial. And any document that discusses writing for the web wouldn't be complete without a nod toward useit.com. The following articles may be of specific interest: There are many, many resources for writing web documents--a quick web search for "web writing" will find lots of resources. Don't get too distracted, though: the ultimate goal is to write, not to read about writing!4.1.1. Writing Style and Style GuidesThere are a number of industry style guides which define how language should be used in documents. A common example for American English is the Chicago Manual of Style. It defines things like: whether a period (.) should be inside or outside of "quotes"; and the format for citing another document. A style guide helps to keep documents consistent--most corporations will follow a style guide to format media releases and other promotional material. Style guides mays also define how words should be spelled (is it color or colour?). The LDP does not require a specific style guide; however, you should use a consistent style throughout your document. Your document should be spell checked for a single language (e.g. American English vs. British English). The Reviewer's HOWTO currently lists a number of conventions for LDP documents and it is as close as it gets to an official LDP Style Guide.
You can save yourself a lot of time in the editing phase if you decide how you will write your document ahead of time. If you are taking over someone else's document you may need to either: modify your own style to fit the current document; or edit the document so that it melds with the style you would like to use from now on. From a writing style perspective, use of the first-person in a HOWTO adds to its charm--an attribute most other documentation sorely lacks. Don't be afraid to speak for yourself--use the word "I" to describe your personal experiences and opinions. 4.2. Edit and Proofread the TextOnce you've written the text of your HOWTO, it is time to polish and refine it. Good editing can make the difference between a good HOWTO and a great one. One of the goals of editing is to remove [extraneous] material that has crept its way into your document. You should go through your HOWTO carefully, and ruthlessly delete anything that does not contribute to the reader's understanding of the subject matter. It is natural for writers to go off on tangents while in the process of writing. Now is the time to correct that. It often helps to leave a bit of time between when you write a document and when you edit it. Make sure that the content of every section matches the title precisely. It's possible that your original subject heading is no longer relevant. If you've strayed from your original heading it could mean one of the following: the original title was poorly worded, the new material should actually go in a different section, or the new material is not really necessary for your document. If you need to change a title, check to see if the original subject heading is still important. If it is, make sure that topic is covered somewhere else in the document. When editing and proofing your work, check for obvious mistakes, such as spelling errors and typos. You should also check for deeper, but less obvious errors as well, such as "holes" in the information. If you are creating a set of instructions it may help to test them on a new machine. Sometimes there are packages that need to be installed which you've forgotten to mention in your documentation, for instance. When you are completely satisfied with the quality and accuracy of your work, forward it to someone else for third-party proofing. You will be too close to the work to see fundamental flaws. Have others test the instructions as well. Make sure they follow exactly what you have written. Ask anyone who tests your documentation to make specific notes in any places where they didn't follow your instructions (and the reason why they didn't follow them). For example: "I skipped step 2 because I already have the required packages installed." In a sense, editing is like code review in software development. Having a programmer review their own code doesn't make much sense, and neither does having a writer edit their own document. Recruit a friend, or write the discuss list to find a volunteer to proofread before submitting your document. You may also want to submit your document to a mailing list that is relevant to your document's topic. List members should be able to help check the facts, clarity of your instructions and language of the document.
4.3. Tools for Writing, Editing and Maintaining your Document
4.3.1. Editing ToolsYou may use any word processing or text editing tool to write your initial document. When you get to the markup stage you may want to use a text editor which recognizes DocBook files. At a minimum a program which adds syntax highlighting to your markup will make life a lot easier. For a description of editors which can handle DocBook files please skip to Section B.2. 4.3.2. Concurrent Versions System (CVS)The LDP provides optional CVS access to its authors. This enables collaborative writing and has the following positive effects:
For more information on how to use CVS to maintain your LDP documents, please read Appendix C. 4.3.3. Spell CheckSome writing tools will come with their own built-in spell check tools. This list is only if your application does not have a spell check option. Spell Check Software
Chapter 5. Markup5.1. Markup: A General OverviewA markup language is a system for marking or tagging a document to define the structure of the document. You may add tags to your document to define which parts of your document are paragraphs, titles, sections, glossary items (the list goes on!). There are many markup languages in use today. XHTML and HTML will be familiar to those who author web documents. The LDP uses a markup language known as DocBook. Each of these markup languages uses its own "controlled vocabulary" to describe documents. For example: in XHTML a paragraph would be marked up with the tagset <p></p> while in DocBook a paragraph would be marked up with <para></para>. The tagsets are defined in a quasi dictionary known as a Document Type Definition (DTD). Markup languages also follow a set of rules on how a document can be assembled. The rules are either SGML (Standard Generalized Markup Language) or XML (eXtensible Markup Language). These rules are essentially the "grammar" of a document's markup. SGML and XML are very similiar. XML is a sub-set of SGML, but XML requires more precise use of the tags when marking up a document. The LDP accepts both SGML and XML documents, but prefers XML. There are three components to an XML/SGML document which is read by a person.
5.2. DocBook: What it is and why we use itAccording to the official DocBook web site,
Although there are other DTDs used to write documentation, there are a few reasons not to use them.
Still not convinced? Eric Raymond has written a DocBook Demystification HOWTO which may help. Convinced, but still not comfortable with the thought of working with DocBook? Give David Lawyer's Howtos-with-LinuxDoc-mini-HOWTO a try. 5.3. XML and SGML: Why we use XMLDocBook comes in a couple of different flavors--including both XML and SGML formats. This means that you may use either the SGML grammar/rules when adding markup, or you may use the XML grammar/rules. Either way you may only use one set of rules throughout your document, and you must define which one you are using at the top of your document. The LDP prefers the XML flavor of DocBook. There are a number of reasons for this including the following:
Still not convinced? Fortunately the LDP does accept a number of other file formats for input. The list of accepted markup languages can be found in Section 5.4 5.4. Markup Languages Accepted by TLDPThe LDP stores its documents in the following markup languages:
Chapter 6. Distributing Your Documentation6.1. Before Distributing Your DocumentationBefore you distribute your documentation, there are a few more things that you will need to check and possibly add to your document.
6.2. Licensing and CopyrightIn order for a document to be accepted by the LDP, it must be licensed and conform to the "LICENSE REQUIREMENTS" section of the LDP Manifesto located at http://www.tldp.org/manifesto.html. We recommend using the GNU Free Documentation License (GFDL), one of the Creative Commons Licenses (Share-Alike, or Attribution-Share-Alike), or the LDP license (currently under review). The full text of the license must be included in your document, including the title and version of the license you are using. The LDP will not accept new documents that do not meet licensing requirements.
You can get DocBook markups of both the GNU GPL and the GNU FDL from the GNOME Documentation Project. You can then merely include the license in its entirety in your document. A DocBook-formatted copy of the license is available in Appendix A. For more information about open source documentation and licensing, please check . 6.2.1. CopyrightAs an author, you may retain the copyright and add other restrictions (for example: require approval for any translations or derivative works). If you are a new maintainer of an already-existing HOWTO, you must include the previous copyright statements of the previous author(s) and the dates they maintained that document. 6.2.2. DisclaimerIf you would like to include a disclaimer, you may choose to use the following:
6.3. AcknowledgmentsYour document should have an "Acknowledgments" section, in which you mention everyone who has contributed to your document in any meaningful way. You should include translators and converters, as well as people who have sent you lots of good feedback, perhaps the person who taught you the knowledge you are now passing on, and anybody else who was instrumental in making the document what it is. Most authors put this section at the end of their document. When someone else assists in the production of an LDP document, you should give them proper attribution, and there are DocBook tags designed to do this. This section will show you the tags you should use, as well as other ways of giving credit where credit is due. Crediting editors is easy - there is already an <editor>tag in DocBook. But there are two special cases where you need to credit someone, but DocBook doesn't provide a special tag. These are translators and converters. A converter is someone who performs a source code conversion, for instance from HTML to DocBook XML. Source code conversions help the LDP achieve long term goals for meta-data, and allow us to distribute documentation in many different formats. Translators take your original document and translate it into other human-readable languages, from English to Japanese for example, or from German to English. Each translation allows many more people all over the world to make use of your document and of the Linux operating system! We recommend that you acknowledge converters in the comment for the initial version released in the new format, and we recommend that you credit translators in each version which they have translated.
6.4. TLDP Review ProcessBefore your document is accepted to the LDP collection it will undergo at least three formal reviews. These reviews include a technical accuracy review, a language review and a metadata review. All new documents must pass these reviews before being accepted into the collection. When you feel your document is finished, email a copy to the submit mailing list (<submit@en.tldp.org>). Please include the title of your document and "Final Review Required" in the subject line of your email. A team of volunteers will be assigned to your document for each of the reviews. It may take up to a week to gather a team who is qualified to review your document. Typically the technical review happens first, followed by the language review and finally the metadata review. Your reviewers will read your document give you feedback on whether or not they think your document is ready for publication in the LDP collection. Your reviewers may have specific points that must be changed. Once you have made the changes submit your document back to your review team. They will review the document again and advise you on whether or not your document is ready for inclusion in the LDP collection. You may need to undergo several edits before your document is ready. Or it may not require any additional work. Be prepared to make at least one round of changes for both the technical and language reviews. Ideally this exchange will happen in the LDP's CVS to better track each of the changes that are made, and keep track of the most current version of your document. Once your document has passed both the technical and language reviews, you may submit it by following the instructions in Section 6.5.
For more information on what the reviewers will be looking for, please read the Linux Documentation Project Reviewer HOWTO. 6.5. Submission to LDP for publication
As part of the review process a Review Coordinator will add your document to the CVS (including any associated image files) and notify the submit mailing list that your document is ready for publication. If you do not already have a CVS account, please apply for one when your document is submitted for publication. You can apply for an account at: http://tldp.org/cvs/ Chapter 7. Maintenance7.1. Maintaining Your DocumentJust because your document has now been published does not mean your job is done. Linux documentation needs regular maintenance to make sure it is up to date, and to improve it in response to readers' ideas and suggestions. TLDP is a living, growing body of knowledge, not just a publish-and-forget-it static entity. Add relevant mailing lists to your document where people can get support. If you have the time, follow these mailing lists yourself to stay up-to-date on the latest information. Put your email address in the document, and politely request feedback from your readers. Once you are officially published, you will begin to receive notes with suggestions. Some of these emails will be very valuable. Create a folder in your mail program for incoming suggestions--when the time is right review the folder and make updates to your document. If you are following a related mailing list you may also choose to save a copy of important emails from the list to this folder.
7.2. Fixing Errors7.2.1. Fixing Your Own DocumentsIf you find an error in your own document, please fix it and re-submit the document. You can re-submit your files by emailing them to <submit@en.tldp.org>. If you have been using the CVS, you can submit your changes to the CVS tree and then send a note to the submit mailing list (<submit@en.tldp.org>). In your email please give the exact path of your document in the CVS tree. Remember to update the revision history at the top of the document. 7.2.2. Fixing Other Documents in the CollectionIf you find an error in someone else's document please contact the author of the document with the correction. If you do not hear back from the author within a "reasonable" amount of time, please email the LDP coordinator at <discuss@en.tldp.org> (subscription required) and describe the problem and how you think it needs to be fixed. If the license permits, you may be asked to make the change directly to the document. If the problems are serious, the document may be removed from the collection, or moved to the "Unmaintained" section.
ReferencesMarkup and general informationSecret Life of Markup, The, http://hotwired.lycos.com/webmonkey/02/42/index4a.html, Steve Champeon. Progressive Enhancement and the Future of Web Design: Where We Are Now , http://hotwired.lycos.com/webmonkey/03/21/index3a_page2.html, Steve Champeon. DocBook ReferencesDocBook XML 4.1.2 Quick Start Guide, http://www.jimweller.net/jim/dbxmlqs/index.html, Jim Weller.
Installing And Using An XML/SGML DocBook Editing Suite Setting Up A Free XML/SGML DocBook Editing Suite For Windows And Unix/Linux/BSD, http://supportweb.cs.bham.ac.uk/documentation/tutorials/docsystem/build/tutorials/docbooksys/docbooksys.html , Ashley J.S. Mills, 2002. Getting Upto Speed With DocBook, http://supportweb.cs.bham.ac.uk/documentation/tutorials/docsystem/build/tutorials/UniDocBook/UniDocBook.html, Ashley J.S. Mills, 2002. DocBook: The Definitive Guide, http://www.docbook.org/, Norman Walsh, Leonard Muellner, 1999, 1-56592-580-7, O'Reilly & Associates, Inc.. This book was released by O'Reilly in October 1999, and is a great reference to DocBook. I have not found it to be a great practical book. You can pick it up at the book vendor of choice, and the entire book is also available online (in HTML and SGML formats) at the above URL. Simplified DocBook: The Definitive Guide, http://www.docbook.org/tdg/simple/en/html/sdocbook.html, Norman Walsh, Leonard Muellner, 1999. Simplified DocBook, http://www.oasis-open.org/docbook/xml/simple/. XML Matters: Getting started with the DocBook XML dialect, http://www-106.ibm.com/developerworks/xml/library/xml-matters3.html. FAQ for DocBook markup, http://www.dpawson.co.uk/docbook/markup.html. Single-Source Publishing with DocBook XML, , http://www.lodestar2.com/people/dyork/talks/2002/ols/docbook-tutorial/frames/frames.html, Dan York, 2002. DocBook Install mini-HOWTO, http://tldp.org/HOWTO/mini/DocBook-Install/, Robert Easter. Exploring SGML DocBook, http://lwn.net/2000/features/DocBook/, Giorgio Zoppi. LinuxDocHowtos-with-LinuxDoc-mini-HOWTO, http://www.tldp.org/HOWTO/Howtos-with-LinuxDoc.html, David Lawyer. LinuxDoc-SGML User's Guide, http://www.nmt.edu/tcc/doc/guide.html. Converting Other Formats to DocBookConverting HTML to Docbook SGML/XML Using html2db, http://www.cise.ufl.edu/~ppadala/tidy/. 5-Minute Review: Using LyX for Creating DocBook, http://www.teledyn.com/help/XML/lyx2db/t1.html. Document processing with LyX and SGML, http://www.karakas-online.de/mySGML/. LDP templates, tools & linksLDP Templates, , http://www.tldp.org/authors/index.html#resources . Contains links to SGML templates and their resulting HTML output to help you see what your document will look like. Many of the tags just need to be replaced with information unique to your HOWTO. Also contains links to tools and other useful information. Linux Documentation Project HOWTO Generator, The, http://www.nyx.net/~sgjoen/The_LDP_HOWTO_Generator.html. This is a standalone web page with a number of fields to fill in and a few buttons. When ready the compile button starts the compilation of all the input fields and wraps it all in proper LinuxDoc SGML, ready to process with the LinuxDoc SGML tools. The compiled output is outputted to a read-only text area near the bottom of the webpage, so the text has to be copied and pasted into a file for compilation. DocBook is not currently supported. DocBook TransformationsDocBook XML/SGML Processing Using OpenJade, , http://tldp.org/HOWTO/DocBook-OpenJade-SGML-XML-HOWTO/, Saqib Ali. General Writing Links and Style GuidesGuide to Grammar and Style, http://newark.rutgers.edu/~jlynch/Writing/, Jack Lynch. Purdue's Online Writing Lab, http://owl.english.purdue.edu/. Chicago Manual of Style, http://www.chicagomanualofstyle.org/. Plain Language Resources, http://www.plainlanguagenetwork.org/Resources/. Writing User-Friendly Documents, http://www.blm.gov/nhp/NPR/pe_toc.html. This is quite useful. It includes before and after writing samples. PlainTrain Writing Tutorial, http://www.web.net/~plain/PlainTrain/IntroducingPlainLanguage.html. Writing for the Web, http://www.useit.com/papers/webwriting/. Information Pollution, http://useit.com/alertbox/20030811.html. Be Succinct! (Writing for the Web), http://useit.com/alertbox/9703b.html. Politics and the English Language, http://www.k-1.com/Orwell/index.cgi/work/essays/language.html, George Orwell. A classic text on writing. A Short Handbook and Style Sheet, http://newark.rutgers.edu/~jlynch/Writing/m.html#mechanics, Thomas Pinney. Technical Writing Links, http://www.techcomplus.com/tips.htm. Technical Writing Tutorial, http://psdam.mit.edu/rise/tutorials/writing/technical-writing.html. Strategies to succeed in technical writing, http://www.school-for-champions.com/techwriting.htm. User Guides Online Tutorial, http://www.klariti.com/technical-writing/User-Guides-Tutorial.shtml. DMOZ Technical Writing Links, http://dmoz.org/Arts/Writers_Resources/Non-Fiction/Technical_Writing/. techwr-L, http://www.raycomm.com/techwhirl/magazine/. Technical Writing Links, http://academic.middlesex.cc.ma.us/PeterHarbeson/links.html. An omnibus of links--scrounge for goodies. Related TLDP DocumentsLinux Documentation Project (LDP) FAQ, http://tldp.org/FAQ/LDP-FAQ/index.html, Rahul Sundaram. LDP HOWTO-INDEX, http://tldp.org/HOWTO/HOWTO-INDEX/, Guylhem Aznar, Joshua Drake, Greg Ferguson. Software: CVSCVS: Project Management, http://doc.cs.byu.edu/programming/cvs/, Byron Clark. CVS, http://supportweb.cs.bham.ac.uk/documentation/tutorials/docsystem/build/tutorials/cvstute/cvstute.html, Ashley J.S. Mills, Alan P. Sexton. CVS--Concurrent Versions System, http://www.loria.fr/~molli/cvs/doc/cvs_toc.html, Pascal Molli. Learning About CVS , http://cvshome.org/docs/. Software: EmacsInformation about PSGML , http://www.lysator.liu.se/~lenst/about_psgml/. Emacs: The Free Software IDE, http://www.linuxjournal.com/article.php?sid=576. Emacs/PSGML Quick Reference, http://www.snee.com/bob/sgmlfree/psgmqref.html, Bob Ducharme. NT Emacs Installation, http://www.charlescurley.com/emacs.html, Charles Curley. Cygwin Packages for DocBook Authoring, http://www.docbook.org/wiki/moin.cgi/CygwinPackages/. SGML for Windows NT: Setting up a free SGML/XML editing and publishing system on Windows/Cygwin , http://ourworld.compuserve.com/homepages/hoenicka_markus/cygbook1.html, Markus Hoenicka, 2000. Vim, http://www.newriders.com/books/opl/ebooks/0735710015.html, Steve Oualline. XML Authoring ToolsSaqib's list of XML Authoring Tools, http://www.xml-dev.com/xml/editors.html. Documentation LicensesLicensing HOWTO, http://www.catb.org/~esr/Licensing-HOWTO.html, Eric Raymond, Catherine Raymond.
Creative Commons, http://creativecommons.org/licenses/by-sa/1.0/. GNU Free Documentation License, http://www.gnu.org/copyleft/fdl.html. GNU General Public License, http://www.gnu.org/licenses/licenses.html#GPL. If you would like your documents to be included in the main Debian distribution, you should use this license. It is not, however, the LDP's license of choice. Appendix A. TemplatesThe LDP stores its documents in the following markup languages:
A.1. Document Templates
A.2. Style SheetsThe following style sheets can be used to make your document nicer to look at. Remember that the LDP will use its own style sheets to distribute your documentation.
A.3. GNU Free Documentation LicenseThe GFDL (GNU Free Documentation License) is available in XML format at http://www.gnu.org/licenses/fdl.xml. For a version in appendix format suitable for including in your document, you can see get the XML for this document from CVS at http://cvsview.tldp.org/index.cgi/LDP/guide/docbook/LDP-Author-Guide/fdl-appendix.xml. TLDP template files for DocBook (XML and SGML) and Linuxdoc SGML are available from the TLDP website at http://www.tldp.org/authors/index.html#resources. Appendix B. System Setup: Editors, Validation and TransformationsIn this section, we will cover some of the tools that you may want to use to create your own LDP documentation. If you use some other tool to assist you in writing documents for the LDP, please drop us a line and we'll add a blurb for it here. Section 1.3 has contact information. B.1. Tools for your operating systemA few notes on setting up your system for DocBook publishing. These tools focus more on the transformation of documents from DocBook to XHTML (for example). Tools For Your Operating System
B.2. Editing toolsEditing tools have come a long way in their support for XML (and specifically DocBook). There are two types of editors outlined in this section: text editors (emacs, vim, etc); and word processors (OpenOffice, AbiWord, etc). New authors who are not comfortable working with markup languages should probably choose a word processor that can output DocBook files. For this reason the word processors are listed first. Although many editors can also validate your DocBook files, this information has been separated into Section B.3.
B.2.1. Word ProcessorsEven if you are not comfortable working DocBook's tagset in a text editor you can still produce valid DocBook documents using a word processor. Support at this point is very limited, but it does exist in the following programs. The up side, of course, is that things like spell check are built in to the program. In addition to this, support for DocBook (and XML) is constantly improving.
B.2.1.1. AbiWordThrough word of mouth I've heard that AbiWord can work (natively) with DocBook documents. This will need to be tested by someone (possibly me) and should definitely be included if it is the case. B.2.1.2. OpenOffice.orgAs of OpenOffice.org (OOo) 1.1RC there has been support for exporting files to DocBook format. Although OOo uses the full DocBook document type declaration, it does not actually export the full list of DocBook elements. It uses a "simplified" DocBook tagset which is geared to on-the-fly rendering. (Although it is not the official Simplified DocBook which is described in Section B.5.) The OpenOffice simplified (or "special" docbook) is available from http://xml.openoffice.org/xmerge/docbook/supported_tag_table.html. B.2.1.2.1. Open Office 1.0.xOOo has been tested by LDP volunteers with mostly positive results. Thanks to Charles Curley (charlescurley.com) for the following notes on using OOo version 1.0.x:
Conclusions: OOo 1.1RC is worth looking at if you want a word processor for preparing DocBook documents. However, I hope they cure the lack of documentation. For one thing, it would be nice to know which native OOo styles map to which DocBook elements. It would also be nice to know how to map one's own OOo styles to DocBook elements. B.2.1.2.2. Open Office 1.1Tabatha Marshall offers the following additional information for OOo 1.1.
B.2.1.3. WordPerfect 9 (Corel Office 2000)WordPerfect 9 for the MS Windows platform has support for SGML and DocBook 3.0. WordPerfect 9 for Linux has no SGML capabilities. If you are using WordPerfect on the Linux operating system, please read: WordPerfect on Linux FAQ B.2.1.4. XMLmind's XML editorhttp://www.xmlmind.com/xmleditor/ Although strictly speaking, it is not a word processor, XMLmind's XML editor allows authors to concentrate on the content, and not the markup. It has built in spelling and conversion utilities which allow you to transform your documents without having to install and configure an additional processing tool such as jade. There is a free "standard edition", which is a simplified version of their "professional edition." B.2.1.5. ConglomerateAccording to their web site, "Conglomerate aims to be an XML editor that everyone can use. In particular, our primary goal is to create the ultimate editor for DocBook and similar formats. It aims to hide the jargon and complexity of XML and present the information in your documents in a way that makes sense." B.2.1.6. Vex: a visual editor for XMLAccording to their web site, "The visual part comes from the fact that Vex hides the raw XML tags from the user, providing instead a wordprocessor-like interface. Because of this, Vex is best suited for document-style XML documents such as XHTML and DocBook rather than data-style XML documents." B.2.2. Text Editors
If you are comfortable working with markup languages and text editors, you'll probably want to customize your current editor of choice to handle DocBook files. Below are some of the more common text editors that can, with some tweaking, handle DocBook files. B.2.2.1. Emacs (PSGML)http://www.lysator.liu.se/~lenst/about_psgml/ Emacs has an SGML writing mode called psgml that is a major mode designed for editing SGML and XML documents. It provides:
For users of Emacs, it's a great way to go. PSGML works with DocBook, LinuxDoc and other DTDs equally well. B.2.2.1.1. Verifying PSGML is InstalledIf you have installed a recent distribution, you may already have PSGML installed for use with Emacs. To check, start Emacs and look for the PSGML documentation (C-himpsgml).
B.2.2.1.2. Configuring Emacs for Use With PSGMLIf you want GNU Emacs to enter PSGML mode when you open an .xml file, it will need to be able to find the DocBook DTD files. If your distribution already had PSGML set up for use with GNU Emacs, you probably won't need to do anything.
Once you've configured your system to use PSGML you will need to override Emacs' default sgml-mode with the psgml-mode. This can be done by configuring your .emacs file. After you've edited the configuration file you will need to restart Emacs. B.2.2.1.3. Creating New DocBook XML FilesThere are a number of steps to creating a new DocBook XML file in Emacs.
B.2.2.1.4. Spell Checking in EmacsEmacs can be configured to use aspell by adding the following to your ~/.emacs file. Thanks to Rob Weir for this configuration information.
B.2.2.2. epcEditThe epcEdit program allows you to edit XML files. It has the advantages of not needing to know Emacs or vi before starting, and is cross-platform, working in both Windows and Linux. This is a commercial application, and pricing can be found at http://www.tksgml.de/pricing.html Along with visual editing, epcEdit will also validate documents on loading, and on demand by using the -> command. B.2.2.3. Morphon XML editorhttp://www.morphon.com/xmleditor/index.shtml This is a commercial application which is currently available for free (with an optional user registration). It is written in Java, allowing it to run on any platform that has a Java Virtual Machine (that is, works in both Windows and Linux). On the plus sides of XMLEditor is the left side of the screen shows the hierarchy of the document (starting with Book and so on). Selecting an item in the list brings you to that part of the document so you can edit it. The right part of the screen shows the text without any markup or tags being shown. If you have external files as ELEMENTS (as the LDP Author Guide does), XMLEditor will follow the links and load the files, so you always work on the entire work. On the minus side of this, you will get errors if a file is missing. B.2.2.4. neditTo be fair, nedit is more for programmers, so it might seem a bit of overkill for new users and especially non-programmers. All that aside, it's extremely powerful, allowing for syntax highlighting. Unlike epcEdit, nedit doesn't allow you to automatically insert tags or automatically validate your code. However, it does allow for shell commands to be run against the contents of the window (as opposed to saving the file, then checking). B.2.2.4.1. Using neditWhen you open your DocBook file, nedit should already have syntax highlighting enabled. If it does not you can turn it on explicitly using: ->-> If you have line numbers turned on (using ->) then finding validation errors is much simpler. nsgmls, the validation tool we'll use, lists errors by their line number. B.2.2.4.2. Configuring neditSince you can feed the contents of your window to outside programs, you can easily extend nedit to perform repetitive functions. The example you'll see here is to validate your document using nsgmls. For more information about nsgmls and validating documents please read Section B.3.
B.2.2.5. VIMNo mention of text editors is complete without talking about vi. The VIM (Vi IMproved) editor has the functionality of regular vi and includes "syntax highlighting" of tags. B.2.2.5.1. Getting StartedThere are many versions of vi. New authors will likely want one of the more feature-packed versions for syntax highlighting and a graphical interface including mouse control. Red Hat users will want the following packages: vim-common, vim-minimal and vim-enhanced. Debian users will want the following package: vim. For an X interface (including GUI menus and mouse control) users will want gvim. The "g" in gvim is for "Graphical". VIM compiles very easy should you need to build your own. Both vim and gvim are built by default. Syntax highlighting is included but not enabled by default if you have to start from scratch; use the :syntax enable command in VIM to turn this feature on. B.2.2.5.2. Creating New DocBook XML FilesIn both vim and gvim, .xml files will be recognized and enter into "SGML mode". A series of known DocBook tags and attributes have been entered into vim and will be highlighted one color if the name is known and another if it is not (for this author the colors are yellow and blue). Having the correct document type declaration at the top of your document should add the syntax highlighting. If you do not see this highlighting you will need to force VIM into SGML mode (even for XML files) using the command :set ft=sgml. If you are working with multiple files for a single XML document you can add your document type in <-- comments --> to the top of the file to get the correct syntax highlighting (you will need to restart the program to see the change in highlighting). The top line of this file (tools-text-editors.xml) looks like this:
B.2.2.5.3. Spell CheckAs in Emacs, Vim, will work quite happily with aspell. It can be run from within Vim with the following: :! aspell -c %. For more sophisticated spell check alternatives, give Cream or vimspell a try. B.2.2.5.4. Tag CompletionThe following information is provided by Kwan Lowe. Vim has a DocBook helper script which can be easily copied into your .vimscripts directory and used to "auto complete" tags while writing DocBook documents. The script can be downloaded from: http://www.vim.org/scripts/script.php?script_id=38.
B.2.2.6. XMLFormhttp://www.datamech.com/XMLForm/ This web-based application allows you to put in the URL for XML source, or copy and paste the XML directly into the web form. The application then breaks down your document into a series of form fields that hide the DocBook tags so that you may edit the content directly. Version 5 is available from http://www.datamech.com/XMLForm/formGenerator5.html. This application is best on shorter documents (less than 20 pages printed). As this is an on-line tool, it will be good for small updates only. B.2.2.7. XMLmind XML Editor (XXE)http://www.xmlmind.com/xmleditor David Horton offers the following information:
B.3. ValidationB.3.1. Why Validate Your DocumentThe LDP uses a number of scripts to distribute your document. These scripts submit your document to the LDP's CVS (a free document version management system), and then they transform your document to other formats that users then read. Your document will also be mirrored on a number of sites worldwide (yet another set of scripts). In order for these scripts to work correctly, your document must be both "well formed" and use "valid markup". Well formed means your document follows the rules that XML is expecting: it complies with XML grammar rules. Valid markup means you only use elements or tags which are "valid" for your document: XML vocabulary rules are applied. If your document is not well formed or uses invalid markup, the scripts will not be able to process it. As a result, your revised document will not be distributed.
B.3.2. Validation for the Faint of HeartYour life is already hard enough without having to install a full set of tools just to see if you validate as well. You can upload your raw XML files to a web site, then go to http://validate.sf.net, enter the URL to your document, then validate it.
B.3.3. Validation for the Not So Faint Of HeartB.3.3.1. CatalogsXML and SGML files contain most of the information you need; however, there are sometimes entities which are specific to SGML in general. To match these entities to their actual values you need to use a catalog. The role of a catalog is to tell your system where to find the files it is looking for. You may want to think of a catalog as a guide book (or a map) for your tools. Most distributions (Red Hat/Fedora and Debian at least) have a common location for the main SGML catalog file, called /etc/sgml/catalog. In times past, it could also be found in /usr/lib/sgml/catalog. The structure of XML catalog files is not the same as SGML catalog files. The section on tailoring a catalog (see Section B.3.4) will give more details about what these files actually contain. If your system cannot find the catalog file, or you are using custom catalog files, you may need to set the SGML_CATALOG_FILES and XML_CATALOG_FILES environment variables. Using echo $SGML_CATALOG_FILES, check to see if it is currently set. If a blank line is returned, the variable has not been set. Use the same command to see if XML_CATALOG_FILES is set as well. If the variables are not set, use the following example to set them now. Example B-1. Setting the SGML_CATALOG_FILES and XML_CATALOG_FILES Environmental Variables
To make this change permanent, you can add the following lines to your ~/.bashrc file.
If you installed XML tools via a RedHat or Debian package, you probably don't need to do this step. If you are using a custom XML catalog you will definitely need to do this. There is more on custom catalogs in the next section. To ensure my backup scripts grab this custom file, I have added mine in a sub-directory of my home directory named "docbook".
You can also change your .bashrc if you want to save these changes.
If you are adding the changes to your .bashrc you will not see the changes until you open a new terminal window. To make the changes immediate in the current terminal, "source" the configuration file. B.3.4. Creating and modifying catalogsIn the previous section I mentioned a catalog is like a guide book for your tools. Specifically, a catalog maps the rules from the public identifier to your system's files. At the top of every DocBook (or indeed every XML) file there is a DOCTYPE which tells the processing tool what kind of document it is about to be processed. At a minimum this declaration will include a public identifier, such as -//OASIS//DTD DocBook V4.2//EN. This public identifier has a number of sections all separated by //. It contains the following information: ISO standard if any (- -- in this case there is no ISO standard), author (OASIS), type of document (DTD DocBook V4.2), language (English). Your DOCTYPE may also include a URL. A public identifier is useless to a processing tool, as it needs to be able to access the actual DTD. A URL is useless if the processing tool is off-line. To help your processor deal with these problems you can download all of the necessary files and then "map" them for your processing tools by using a catalog. If you are using SGML processing tools (for instance Jade), you will need an SGML catalog. If you are using XML processing tools (like XSLT), you will need an XML catalog. Information on both is included. B.3.4.1. SGML CatalogsExample B-2. Example of an SGML catalog
As in the example above, to associate an identifier to a file just follow the sequence shown:
B.3.4.1.1. Useful commands for catalogsThe most common mappings to be used in catalogs are:
B.3.4.2. XML CatalogsThe following sample catalog was provided by Martin A. Brown. Example B-3. Sample XML Catalog file
B.3.5. Validating XMLB.3.5.1. nsgmlsYou can use nsgmls, which is part of the jade suite (on Debian apt-get the docbook-utils package, see Section B.4.2), to validate SGML or XML documents.
If there are no issues, you'll just get your command prompt back. The -s tells nsgmls to show only the errors.
For more information on processing files with Jade/OpenJade please read DocBook XML/SGML Processing Using OpenJade. B.3.5.2. onsgmlsThis is an alternative to nsgmls. It ships with the OpenJade package. This program gives more options than nsgmls and allows you to quietly ignore a number of problems that arise while trying to validate an XML file (as opposed to an SGML file). This also means you don't have to type out the location of your xml.dcl file each time. I was able to simply use the following to validate a file with only error messages that were related to my markup errors.
According to Bob Stayton you can also turn off specific error messages. The following example turns off XML-specific error messages.
B.3.5.3. xmllintYou can also use the xmllint command-line tool from the libxml2 package to validate your documents. This tool does a simple check on completeness of tags and whether all tags that are opened, are also closed again. By default xmllint will output a results tree. So if your document comes out until the last line, you know there are no heavy errors having to do with tag mismatches, opening and closing errors and the like. To prevent printing the entire document to your screen, add the --noout parameter.
If nothing is returned, your document contains no syntax errors. Else, start with the first error that was reported. Fix that one error, and run the tool again on your document. If it still returns output, again fix the first error that you see, don't botter with the rest since further errors are usually generated because of the first one. If you would like to check your document for any errors which are specific to your Document Type Definition, add --valid.
The xmllint tool may also be used for checking errors in the XML catalogs, see the man pages for more info on how to set this behavior. If you are a Mac OSX or Windows user, you may also want to check out tkxmllint, a GUI version of xmllint. More information is available from: http://tclxml.sourceforge.net/tkxmllint.html. Example B-4. Debugging example using xmllint The example below shows how you can use xmllint to check your documents. I've created some errors that I made a lot, as a beginning XML writer. At first, the document doesn't come through, and errors are shown:
Now, as we already mentioned, don't worry about anything except the first error. The first error says there is an inconsistency between the tags on line 6 and line 22 in the file. Indeed, on line 6 we left out the "e" in "articleinfo". Fix the error, and run xmllint again. The first complaint now is about the offending line 37, where the closing tag for list items has been forgotten. Fix the error and run the validation tool again, until all errors are gone. Most common errors include forgetting to open or close the paragraph tag, spelling errors in tags and messed up sections. B.4. Transformations
Still here? Great! Transformations are a pretty basic requirement to get what you've written from a messy tag-soup into something that can be read. This section will help you get your system set up and ready to transform your latest document into other formats. This is very useful is you want to see your document before you release it to the world. There are currently two ways to transform your document: Document Style Semantics and Specification Language (DSSSL); and XML Style sheets (XSLT). Although the LDP web site uses DSSSL to convert documents you may use XSLT if you want. You only need to choose one of these methods. For more information about DSSSL read: Section B.4.1, for more information about XSLT read: Section B.4.3. B.4.1. DSSSLThere are three basic requirements to transform a document using DSSSL:
B.4.1.1. The Style SheetsThere are two versions of the Document Style Semantics and Specification Language used by the LDP to transform documents from your raw DocBook files into other formats (which are then published on the Web). The LDP version of the style sheets requires the Norman Walsh version--which basically means if you're using DSSSL the Norman Walsh version can be considered a requirement for system setup. Norman Walsh DSSSL http://docbook.sourceforge.net/projects/dsssl/. The Document Style Semantics and Specification Language tells Jade (see Section B.4.1.2) how to render a DocBook document into print or on-line form. The DSSSL is what converts a title tag into an <h1> HTML tag, or to 14 point bold Times Roman for RTF, for example. Documentation for DSSSL is located at the same site. Note that modifying the DSSSL doesn't modify DocBook itself. It merely changes the way the rendered text looks. The LDP uses a modified DSSSL (see below). LDP DSSSL http://www.tldp.org/authors/tools/ldp.dsl. The LDP DSSSL requires the Norman Walsh version (see above) but is a slightly modified DSSSL to provide things like a table of contents. B.4.1.2. DSSSL ProcessorsThere are two versions of the Jade processor: the original version by James Clark; and an open-source version of approximately the same program, OpenJade. You only need one of these programs. It should be installed after the DTD and DSSSL have been "installed." DSSSL Transformation Tools
B.4.1.3. System Setup for DSSSL Transformations
B.4.1.4. Transformations with DSSSLOnce your system is configured (see the previous section), you should be able to start using jade to transform your files from XML to XHTML. To create individual HTML files, point jade at the correct DSL (style sheet). The following example uses the LDP style sheet.
If you would like to produce a single-file HTML page, add the -V nochunks parameter. You can specify the name of the final HTML file by appending the command with > output.html.
If you would like to create print-friendly files instead of HTML files, simply change the style sheet that you are using. In the file name above, note "html/ldp.dsl" at the end. Change this to "print/docbook.dsl", or if you want XHTML output, instead of HTML, change the file name to "xhtml/docbook.dsl". B.4.1.4.1. Changing CSS FilesIf you want your HTML files to use a specific CSS stylesheet, you will need to edit ldp.dsl. Immediately after ;; End of $verbatim-display$ redefinition add the following lines:
Replace base.css with the name of the CSS file you would like to use. B.4.2. The docbook-utils PackageThe docbook-utils provide commands like db2html, db2pdf and db2ps, based on the jw scripts, that is a front-end to Jade. These tools ease the everyday management of documentation and add comfortable features. The package, originally created by RedHat and available from http://sources.redhat.com/docbook-tools/ can be installed on most systems. Example B-6. Example creating HTML output After validating your document, simply issue the command db2html mydoc.xml to create (a) HTML file(s). You can also use the docbook-utils as validation tools. Remember: when errors occur, always start by solving only the first problem. The rest of the problems may be fixed when you fix the first error. If you get errors about a function name, please read . B.4.2.1. Using CSS and DSL for pretty outputYou can define your own additional DSL instructions, which can include a pointer to a personalized CSS file. Sample DSL and CSS files are provided in Appendix A. The sample DSL file will create a table of contents, and have all HTML files start with the prefix intro2linux- and end with a suffix of .html. The %stylesheet% variable points to the CSS file which should be called by your HTML file. To use a specific DSL style sheet the following command should be used: db2html -d mystyle.dsl mydoc.xml You can compare the result here: http://tille.xalasys.com/training/unix/ is a book formatted with the standard tools; http://tille.xalasys.com/training/tldp/ is one using personalized DSL and CSS files. Soft tones and special effects, for instance in buttons, were used to achieve maximum effect. B.4.3. XSLThere are alternatives to DSSSL and Jade/OpenJade. When working with DocBook XML, the LDP offers a series of XSL[2] style sheets to process documents into HTML. These style sheets create output files using the XML tool set that are similar to those produced by the SGML tools using ldp.dsl. The major difference between using ldp.dsl and the XSL style sheets is the way that the generation of multiple files is handled, such as the creation of a separate file for each chapter, section and appendix. With the SGML tools, such as jade or openjade, the tool itself was responsible for generating the separate files. Because of this, only a single file, ldp.dsl was necessary as a customization layer for the standard DocBook DSSSL style sheets. With the DocBook XSL style sheets, generation of multiple files is controlled by the style sheet. If you want to generate a single file, you call one style sheet. If you want to generate multiple files, you call a different style sheet. For that reason the LDP XSL style sheet distribution is comprised of four files:
You can find the latest copy of the files at http://my.core.com/~dhorton/docbook/tldp-xsl/. The package includes installation instructions which are duplicated at http://my.core.com/~dhorton/docbook/tldp-xsl/doc/tldp-xsl-howto.html. The short version of the install instructions is as follows: Download and unzip the latest package from the web site. Take the files from the html directory of TLDP-XSL and put them in the html directory of Norman Walsh's stylesheets. Take the file from the TLDP-XSL fo directory and put it in the Norman Walsh fo directory. Once you have installed these files you can use xsltproc to generate HTML files from your XML documents. To transform your XML file(s) into a single-page HTML document use the following command:
To generate a set of linked HTML pages, with a separate page for each chapter, sect1 or appendix, use the following command:
Note that you never directly call the style sheet tldp-html-common.xsl. It is called by both of the other two style sheets. B.5. DocBook DTDThe DocBook DTD defines the structure of a DocBook document. It contains rules about how the elements may be used; and what the elements ought to be describing. For example: it is the DocBook DTD which states all warnings are to warn the reader (this is the definition of the element); and may not contain plain text (this is the content model--and the bit which forces you to wrap your warning text in a para or perhaps a list).
The XML DTD is available from http://www.oasis-open.org/xml/4.2/. The LDP prefers this version of the DocBook DTD. If you are going to be working with SGML versions of DocBook you will need one (or both) of: http://www.oasis-open.org/docbook/sgml/4.1/docbk41.zip or http://www.oasis-open.org/docbook/sgml/3.1/docbk31.zip Example B-7. "Installing" DocBook Document Type Definitions Create a base directory to store everything such as /opt/local/sgml/. Copy the DTDs into a sub-directory named dtd.
B.6. Formatting DocumentsB.6.1. Inserting a summary on the initial articles pageA feature that might be valuable in some cases is the insertion of the summary on the initial page of an article. DocBook articles do not include it as a standard feature. To enable this, it is necessary to modify the style sheet file. Example B-8. Style sheet to insert summaries in articles
B.6.2. Inserting indexes automaticallyAlthough DocBook has markups for the composition of them, indexes are not generated automatically. The collateindex.pl command allows indexes to be generated from the source DocBook for inclusion into the finished/transformed document.
For the above example to work, it is necessary to define an external entity by calling the file index.sgml. Example B-9. Configuring an external entity to include the index
See also Section D.4 for information on how to insert necessary information on the text.
Appendix C. Concurrent Version System (CVS)The LDP provides optional CVS access to its authors. This enables collaborative writing and has the following positive effects:
You can browse the LDP CVS repository via the web at http://cvsview.tldp.org/. C.1. Getting a CVS account
If you qualify for a CVS account you may apply for one using the form at http://tldp.org/cvs/ Include information about which documents you maintain. Remember your password, it will not be sent in the confirmation email. C.2. Using CVSC.2.1. Setting Up Your CVS AccountFirst you'll need to get an account at the LDP's CVS Repository. Please see the notes above on obtaining an account. This repository houses various documents including HOWTOs and Guides. Documents are sorted by the type of document (for example a HOWTO or a Guide), and by the markup language the document uses (for example DocBook or LinuxDoc). When your account is ready you can log in using one of the following commands. In all instances your_userid should be replaced by the user name you were issued in the response email. You will be prompted for a password after this first step. Initializing Your CVS Account
Wait patiently while the system tries to log you in. It can often take more that 10-20 seconds for the system to either accept (or reject) your password. Once you've used cvs login for the first time and have been given access to the system, your password is stored in .cvspass and you will not have to use cvs login again. Just set the CVSROOT with the export command listed above and continue on. If TLDP's CVS server is the only one you work with, you might also add an export CVSROOT line to your ~/.bashrc shell configuration file. C.2.2. Getting the DocumentsYou can get the entire repository with: cvs checkout LDP Or you can get the source for your own document with: cvs checkout LDP/howto/docbook/YOUR-HOWTO.xml OR cvs checkout LDP/guide/docbook/YOURGUIDE Windows users will need to use a modified version of this command. Instead they should use: cvs -d %CVSROOT% checkout LDP/howto/docbook/YOUR-HOWTO.xml
C.2.3. CVS CommandsCVS Commands: a brief reminder
If you need to change a file name, you still need to use the add command. First remove the copy of the file from your local disk. Then remove it from the CVS tree with: cvs remove filename. As with the add command, you need to >commit your removed file. Finally, now that the old file has been removed, add your new file using the instructions above (first add and then commit the additional file). C.2.3.1. Recovering old versionsThere you are, typing away, when you screw up. Real bad. Doesn't matter what it is, but suffice it to say that you've toasted not only the version on your local drive, but created a new version on the CVS server. What you need to do is go back in time and resurrect an older version of your file. To do this, you'll need to know the version number of the file you want to retrieve. cvs diff will give a list of revisions if there are differences. You can pick the revision number, subtract one, and that is probably the revision you want to look at. The command cvs -Q update -p -r revision filename will output to stdout the contents of the revision version of filename. You can pipe it to more or redirect the output to a file. Conveniently, you can redirect stdout to a file called filename. Your local file is now the revision you want, and cvs update will update the CVS server with the new (old) version of filename. Appendix D. DocBook: Sample MarkupD.1. General Tips and TricksFor a general overview of what markup is all about, please read Chapter 5
D.1.1. Useful markupTable D-1 shows some markup that is useful for generating generic documents. Remember that some elements are valid only on some contexts.
Table D-1. Useful markup
D.2. <section> and <sectN>: what's the difference?
<section> versus <sectN> is largely a question of flexibility. The stylesheets can make a <section> in a <section> look just like a <sect2> within a <sect1>, so there's no output advantage. But, a <section> within a <section> can be extracted into its own top-level section, nested even more deeply, or moved to an entirely different part of the document, without it and its own <section> children being renamed. That is not true of the numbered section tags, which are very sensitive to rearrangements. This can be easier for authors who are new to DocBook than using <sectN>. The main idea behind creating structured data is that it should be easy to access and query. One should be able to retrieve a subsection of any structured data, by using querying languages for XML (XPath and XQuery). <sectN> are useful when traversing a document using XPath/XQuery. <sectN> gives more flexibility, and control while writing an XPath expression. A well-defined, valid and well-structured document makes it easier for one to write XPath/Query to retreive "specific" data from a document. For example you can use XPath to retrieve information in the <sect3> block with certain attributes. However if you just used <section> for all subsections, it becomes harder to retrieve the block of information that you need. So which one should you use? The one you feel most comfortable with is a good place to start. This document is written with <section>s. You may, or may not, think this is a good idea. :) D.3. Command PromptsThere are likely as many ways of doing this as there are DocBook authors; however, here are two ways that you might find useful. Thanks to Y Giridhar Appaji Nag and Martin Brown for the markup used here. Example D-1. Command Prompt with programlisting
Displays as:
Example D-2. Command Prompt with screen First create a general entity in the internal subset at the very beginning of your document. This entity will define a name for the shortcut which you can use to display the full prompt at any point in your document. <!ENTITY prompt "<prompt>[user@machine ~/dir]$</prompt>"> For more information about entities, read Section D.8.
Displays as:
If you would like to add the output of your commands you can add <computeroutput> text</computeroutput> within the <screen> or <programlisting> as appropriate. D.4. Encoding IndexesThe generation of indexes depends on the markups inserted in the text. Such markups will be processed afterwards by an external tool and will generate the index. An example of such a tool is the collateindex.pl script (see Section B.6.2). Details about the process used to generate these indexes are shown in Section B.6.2. The indexes have nesting levels. The markup of an index is done by the code Example D-3. Example D-3. Code for the generation of an index
It is possible to refer to chapters, sections, and other parts of the document using the attribute zone. Example D-4. Use of the attribute zone
The Example D-4 has the code used to generate the entry of this edition on the index. In fact, since the attribute zone is used, the index statement could be located anywhere in the document or even in a separate file. However, to facilitate maintenance the entries for the index were all placed after the text to which it refers. Example D-5. Usage of values startofrange and endofrange on the attributeclass
D.5. Inserting PicturesIt is necessary to insert pictures formats for all possible finished document types. For example: JPG files for web pages and EPS for PostScript and PDF files. If you use the TeX format you'll need the images as a PostScript file. For on-line publishing you can use any kind of common image file, such as JPG, GIF or PNG. The easiest way to insert pictures is to use the fileref attribute. Usually pictures are generated in JPG and in PostScript (PS or EPS). Example D-6. Inserting a picture
Replacing <figure> by <informalfigure> eliminates the need to insert a title for the picture. There's still the float attribute on which the value 0 indicates that the picture should be placed exactly where the tag appears. The value 1 allows the picture to be moved to a more convenient location (this location can be described on the style sheet, or it can be controlled by the application). D.5.1. Graphics formatsWhen submitting graphics to the LDP, please submit one set of graphics in .eps, and another in .gif, .jpg or .png. The preferred format is .png or .jpg due to patent problems with .gif. You can use .jpg files for continuous-tone images such as photos or images with gradual changes in color. Use .png for simple images like diagrams, some screen shots, and images with a low number of colors. D.5.2. Alternative MethodsThe first alternative to Example D-6 is to eliminate the <figure> or <informalfigure> elements. Another interesting alternative when you have decided to publish the text on media where pictures are not accepted, is the use of a wrapper, <imageobject>. Example D-7. Using <imageobject>
Files using the following formats are available BMP, CGM-BINARY, CGM-CHAR, CGM-CLEAR, DITROFF, DVI, EPS, EQN, FAX, GIF, GIF87A, GIF89A, IGES, JPEG, JPG, LINESPECIFIC, PCX, PIC, PS, SGML, TBL, TEX, TIFF, WMF, WPG. This method presents an advantage: a better control of the application. The elements <imageobject> are consecutively tested until one of them is accepted. If the output format does not support images the <textobject> element will be used. However, the biggest advantage in usage of the format Example D-7 is that in DocBook 5.0, the <graphic> element will cease to exist. As a disadvantage, there is the need for more than one representation code of the same information. It is up to the author to decide how they will implement illustrations and pictures in the document, but for compatibility with future versions I recommend the use of this method for pictures and graphics.
D.6. Markup for MetadataD.6.1. Crediting Translators, Converters and Co-authorsThere are several ways that these folks, as well as other contributors to your document, can be given some recognition for the help they've given you. D.6.1.1. <othercredit>All translators, converters and co-authors should be credited with an <othercredit> tag entry. To properly credit a translator or converter, use the <othercredit> tag with the role attribute set to "converter" or "translator", as indicated in the example below: D.6.2. <revremark>sWithin the <revision> tag hierarchy is a tag called <revremark>. Within this tag, you can make any brief notes you wish about each particular revision of your document. D.6.3. Revision HistoryThe <revhistory> tag should be used to denote the various revisions of the document. Specify the date, revision number and comments regarding what has changed. Revisions should be listed with the most-recent version at the top (list in descending order). D.6.4. Date formatsThe <pubdate> tag in your header should list the publication date of this particular version of the document (coincide with the revision date). It should be in the following format:
The date is in the format YYYY-MM-DD, which is one of the ISO 8601 standard formats for representing dates. For you Yanks out there (me too), think of it as going from the largest unit of time to the smallest. D.6.5. Sample Article (or Book) Information ElementHere is a sample of a complete DocBook (SGML or XML) <articleinfo> element which contains some of the items and constructs previously described. Example D-10. Sample Meta Data
D.7. BibliographiesNot everyone will choose to use the correct formatting for a bibliography. Most will use a list of some kind. And that's ok. But when you're ready to move to the next level, here's how to do it. Below are two examples of bibliographic entries. The first is a very simple entry. It has only a title, URL and possibly a short description (abstract). The second is a little more complex and is for a full entry (for instance a book) with an ISBN, publisher and copyright date.
Example D-11. A Bibliography
View References to see this in action. D.8. Entities (shortcuts, text macros and re-usable text)There may be some segments of text, or markup that you want to use over and over again. Instead of typing it up multiple times (and then having to edit it multiple times if you want to make a change) you can use external entities. Entities can give you a short cut to: re-using whole documents, text snippets, and special markup. Some common ways to use an entity would be for:
Example D-12. Adding Entities
To use these entities simply insert the name you gave the entity between a "&" (ampersand) and a ";" (semicolon). For example: "&shortcut;" would expand into "Replace 'shortcut' with this text"; "&sc-to-a-file;" would include the full contents of whatever is in anotherfile.xml. An important feature while writing a text is the ability to check whether or not it will be presented in the final draft. It is common to have several parts of the text marked as draft, especially when updating an already existing document. With the use of parameter entities, you can include or eliminate these drafts by altering only one line at the beginning of a document. Example D-13. Use of parameter entities
The entity review might have several texts defined, as in Example D-13. When the changes to the text are considered final, you need only to remove parts of the text between the 3rd. and 6th. lines. To keep the draft definitions and hide the text in the final draft, just alter the specification of the entity from INCLUDE to IGNORE. D.9. Customizing your HTML filesD.9.1. HTML file namesBy default, when separate HTML files are made, the SGML processor will assign arbitrary names to the resulting files. This can be confusing to readers who may bookmark a page only to have it change. Whatever your reasoning, here's how to make separate files named the way you want: In your first <article> tag (which should be the only one) include an id parameter and call it "index". This will make your tag look like this:
Do not modify the first <chapter> tag, as it's usually an introduction and you want that on the first page. For each other <section> tag, include the id parameter and name it. A name should include only alphanumeric characters, and it should be short enough to understand what it is.
D.9.2. Headers and FootersThere is no "easy" way to add headers and footers to your document. If you are using DocBook XSL and doing your own document transformations you may customize the XSL template to suit your needs. For more information read http://www.sagehill.net/docbookxsl/HTMLHeaders.html. Appendix E. Converting Documents to DocBook XMLA variety of free and commercial tools exist for doing "up conversion" of non-XML formats to DocBook. A few are listed here for your convenience. A more comprehensive list is available from Convert Other Formats to DocBook. E.1. Text to DocBookThe txt2docbook tool allows one to convert a ascii (README-like) file to a valid docbook xml document. It simplifies the publishing of rather small papers significantly. The input format was inspired by the APT-Convert tool from http://www.xmlmind.com/aptconvert.html. The script can be downloaded from http://txt2docbook.sourceforge.net/. E.2. OpenOffice.org to DocBookAs of OpenOffice.org (OOo) 1.1RC there has been support for exporting files to DocBook format. Although OOo uses the full DocBook document type declaration, it does not actually export the full list of DocBook elements. It uses a "simplified" DocBook tag set which is geared to on-the-fly rendering. (Although it is not the official Simplified DocBook which is described in Section B.5.) The OpenOffice simplified (or "special" docbook) is available from http://www.chez.com/ebellot/ooo2sdbk/. E.2.1. Open Office 1.0.xOOo has been tested by LDP volunteers with mostly positive results. Thanks to Charles Curley (charlescurley.com) for the following notes on using OOo version 1.0.x:
Conclusions: OOo 1.1RC is worth looking at if you want a word processor for preparing DocBook documents. However, I hope they cure the lack of documentation. For one thing, it would be nice to know which native OOo styles map to which DocBook elements. It would also be nice to know how to map one's own OOo styles to DocBook elements. E.2.2. Open Office 1.1Tabatha Marshall offers the following additional information for OOo 1.1.
E.3. Microsoft Word to DocBookEven if you want to use MS Word to write your documents, you may find w2XML useful. Note that this is not free software--the cost is around $130USD. There is, however, a trial version of the software. E.4. LaTeX to DocBookSiep Kroonenberg reports that there is a package tex4ht http://www.cse.ohio-state.edu/~gurari/TeX4ht/ that converts TeX and LaTeX to various flavors of XML. Currently, its support for DocBook output is limited. If you want to use tex4ht in its current state for LDP you will probably have to hack your LaTeX source beforehand and the generated XML afterwords. E.5. LyX to DocBookThis section is contributed by Chris Karakas. You can use the LyX-to-X package to write your document conveniently in LyX (a visual editor originally developped as a graphical frontend to LaTeX), then export it to DocBook SGML and submit it to The LDP. This method is presented by Chris Karakas Document processing with LyX and SGML. In the LyX-to-X project, LyX is used as a comfortable graphical SGML editor. Once the document is exported to SGML from LyX, it undergoes a series of transformations through sed and awk scripts that correct the SGML code, computes the Index, inserts the Bibliography and the Appendix and takes care of the correct invocation of openjade, pdftex, pdfjadetex and all the other necessary programs for the generation of HTML (chunked or not), PDF (with images, bookmarks, thumbnails and hyperlinks), PS, RTF and TXT versions. All aspects of document processing are handled, including automatic Index generation, display of Mathematics in TeX quality both online and in print formats, as well as the use of bibliographic databases with RefDB. Special care is taken so that the document processing is as transparent to the user as possible - the aim being that the user writes in LyX, then presses a button, and the LyX-to-X script does the rest. Download the documentation and the LyX-to-X package from the Formats section. E.6. DocBook to DocBook TransformationsE.6.1. XML and SGML DocBookThere are a few changes between DocBook XML and SGML. Handling these differences should be relatively easy for most small documents, and many authors will not need to make any changes to convert their documents other than the XML and DocBook declarations at the start of their document. For others, here is a list of what you should keep in mind when converting your documents from SGML to XML.
E.6.2. Changing DTDsThe significant changes between version changes in the DTD involve changes to the elements (tags). Elements may be: deprecated (which means they will be removed in future versions); removed; modified; or added. Almost all authors will run into a changed or deprecated tag when going from a lower version of DocBook to a higher version. DocBook: The Definitive Guide does an excellent job of showing you how elements fit together. For each element it tells you what an element must contain (its content model) and what is may be contained in (who its parents are). For example: a note must contain a para. If you try to write <note>Content in a note</note> your document will not validate. Learning how elements are assembled will make it a lot easier to understand any validation errors that are thrown at you. If you get truly stuck you can also email the LDP's docbook mailing list for extra hints. Information on subscribing is available from Section 2.2 All tags that have been deprecated or changed for 4.x are listed in DocBook: The definitive guide, published by O'Reilly and Associates. This book is also available on-line from http://www.docbook.org. E.6.2.1. Differences between version 3.x and 4.xHere are a few elements that are of particular relevance to LDP authors:
Glossary
Appendix F. GNU Free Documentation LicenseF.1. 0. PREAMBLEThe 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. F.2. 1. APPLICABILITY AND DEFINITIONSThis 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. F.3. 2. VERBATIM COPYINGYou 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. F.4. 3. COPYING IN QUANTITYIf 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. F.5. 4. MODIFICATIONSYou 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:
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 . F.6. 5. COMBINING DOCUMENTSYou 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." F.7. 6. COLLECTIONS OF DOCUMENTSYou 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 dispbibute 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. F.8. 7. AGGREGATION WITH INDEPENDENT WORKSA 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. F.9. 8. TRANSLATIONTranslation 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. F.10. 9. TERMINATIONYou 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. F.11. 10. FUTURE REVISIONS OF THIS LICENSEThe 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. F.12. AddendumTo 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:
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. Notes
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