Index: head/en_US.ISO8859-1/books/fdp-primer/docbook-markup/chapter.xml =================================================================== --- head/en_US.ISO8859-1/books/fdp-primer/docbook-markup/chapter.xml (revision 42133) +++ head/en_US.ISO8859-1/books/fdp-primer/docbook-markup/chapter.xml (revision 42134) @@ -1,2250 +1,2263 @@ DocBook Markup Introduction This chapter is an introduction to DocBook as it is used for &os; documentation. DocBook is a large and complex markup system, but the subset described here covers the parts that are most widely used for &os; documentation. While a moderate subset is covered, it is impossible to anticipate every situation. Please post questions that this document does not answer to the &a.doc;. DocBook was originally developed by HaL Computer Systems and O'Reilly & Associates to be a DTD for writing technical documentation A short history can be found under http://www.oasis-open.org/docbook/intro.shtml#d0e41.. Since 1998 it is maintained by the DocBook Technical Committee. As such, and unlike LinuxDoc and XHTML, DocBook is very heavily oriented towards markup that describes what something is, rather than describing how it should be presented. The DocBook DTD is available from the Ports Collection in the textproc/docbook-xml-450 port. It is automatically installed as part of the textproc/docproj port. Formal Versus Informal Some elements may exist in two forms, formal and informal. Typically, the formal version of the element will consist of a title followed by the informal version of the element. The informal version will not have a title. Inline Versus Block In the remainder of this document, when describing elements, inline means that the element can occur within a block element, and does not cause a line break. A block element, by comparison, will cause a line break (and other processing) when it is encountered. &os; Extensions The &os; Documentation Project has extended the DocBook DTD by adding some new elements. These elements serve to make some of the markup more precise. Where a &os;-specific element is listed below, it is clearly marked. Throughout the rest of this document, the term DocBook is used to mean the &os;-extended DocBook DTD. There is nothing about these extensions that is &os; specific, it was just felt that they were useful enhancements for this particular project. Should anyone from any of the other *nix camps (NetBSD, OpenBSD, Linux, …) be interested in collaborating on a standard DocBook extension set, please get in touch with &a.doceng;. The &os; extensions are not (currently) in the Ports Collection. They are stored in the &os; Subversion tree, as head/share/xml/freebsd.dtd. Formal Public Identifier (FPI) In compliance with the DocBook guidelines for writing FPIs for DocBook customizations, the FPI for the &os; extended DocBook DTD is: PUBLIC "-//FreeBSD//DTD DocBook V4.2-Based Extension//EN" Document Structure DocBook allows structuring documentation in several ways. The &os; Documentation Project uses two primary types of DocBook document: the book and the article. Books are organized into chapters. This is a mandatory requirement. There may be parts between the book and the chapter to provide another layer of organization. For example, the Handbook is arranged in this way. A chapter may (or may not) contain one or more sections. These are indicated with the sect1 element. If a section contains another section then use the sect2 element, and so on, up to sect5. Chapters and sections contain the remainder of the content. An article is simpler than a book, and does not use chapters. Instead, the content of an article is organized into one or more sections, using the same sect1 (and sect2 and so on) elements that are used in books. The nature of the document being written should be used to determine whether it is best marked up as a book or an article. Articles are well suited to information that does not need to be broken down into several chapters, and that is, relatively speaking, quite short, at up to 20-25 pages of content. Books are best suited to information that can be broken up into several chapters, possibly with appendices and similar content as well. The &os; tutorials are all marked up as articles, while this document, the FreeBSD FAQ, and the FreeBSD Handbook are all marked up as books, for example. Starting a Book The content of a book is contained within the book element. As well as containing structural markup, this element can contain elements that include additional information about the book. This is either meta-information, used for reference purposes, or additional content used to produce a title page. This additional information is contained within bookinfo. Boilerplate <sgmltag>book</sgmltag> with <sgmltag>bookinfo</sgmltag> <book> <bookinfo> <title>Your Title Here</title> <author> <firstname>Your first name</firstname> <surname>Your surname</surname> <affiliation> <address><email>Your email address</email></address> </affiliation> </author> <copyright> <year>1998</year> <holder role="mailto:your email address">Your name</holder> </copyright> <releaseinfo>$FreeBSD$</releaseinfo> <abstract> <para>Include an abstract of the book's contents here.</para> </abstract> </bookinfo> … </book> Starting an Article The content of the article is contained within the article element. As well as containing structural markup, this element can contain elements that include additional information about the article. This is either meta-information, used for reference purposes, or additional content used to produce a title page. This additional information is contained within articleinfo. Boilerplate <sgmltag>article</sgmltag> with <sgmltag>articleinfo</sgmltag> <article> <articleinfo> <title>Your title here</title> <author> <firstname>Your first name</firstname> <surname>Your surname</surname> <affiliation> <address><email>Your email address</email></address> </affiliation> </author> <copyright> <year>1998</year> <holder role="mailto:your email address">Your name</holder> </copyright> <releaseinfo>$FreeBSD$</releaseinfo> <abstract> <para>Include an abstract of the article's contents here.</para> </abstract> </articleinfo> … </article> Indicating Chapters Use chapter to mark up your chapters. Each chapter has a mandatory title. Articles do not contain chapters, they are reserved for books. A Simple Chapter The Chapter's Title ... ]]> A chapter cannot be empty; it must contain elements in addition to title. If you need to include an empty chapter then just use an empty paragraph. Empty Chapters This is An Empty Chapter ]]> Sections Below Chapters In books, chapters may (but do not need to) be broken up into sections, subsections, and so on. In articles, sections are the main structural element, and each article must contain at least one section. Use the sectn element. The n indicates the section number, which identifies the section level. The first sectn is sect1. You can have one or more of these in a chapter. They can contain one or more sect2 elements, and so on, down to sect5. Sections in Chapters A Sample Chapter Some text in the chapter. First Section (1.1) … Second Section (1.2) First Sub-Section (1.2.1) First Sub-Sub-Section (1.2.1.1) … Second Sub-Section (1.2.2) … ]]> This example includes section numbers in the section titles. You should not do this in your documents. Adding the section numbers is carried out by the stylesheets (of which more later), and you do not need to manage them yourself. Subdividing Using <sgmltag>part</sgmltag> Elements parts introduce another level of organization between book and chapter with one or more parts. This cannot be done in an article. Introduction Overview ... What is FreeBSD? ... History ... ]]> Block Elements Paragraphs DocBook supports three types of paragraphs: formalpara, para, and simpara. Almost all paragraphs in &os; documentation use para. formalpara includes a title element, and simpara disallows some elements from within para. Stick with para. <sgmltag>para</sgmltag> Usage: This is a paragraph. It can contain just about any other element. ]]> Appearance: This is a paragraph. It can contain just about any other element. Block Quotations A block quotation is an extended quotation from another document that should not appear within the current paragraph. These are rarely needed. Blockquotes can optionally contain a title and an attribution (or they can be left untitled and unattributed). <sgmltag>blockquote</sgmltag> Usage: A small excerpt from the US Constitution:
Preamble to the Constitution of the United States Copied from a web site somewhere We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America.
]]> Appearance: A small excerpt from the US Constitution:
Preamble to the Constitution of the United States Copied from a web site somewhere We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America.
Tips, Notes, Warnings, Cautions, Important Information and Sidebars Extra information may need to be separated from the main body of the text. Typically this is meta information of which the user should be aware. Depending on the nature of the information, one of tip, note, warning, caution, and important should be used. Alternatively, if the information is related to the main text but is not one of the above, use sidebar. The circumstances in which to choose one of these elements over another is loosely defined by the DocBook documentation, which suggests: A Note is for information that should be heeded by all readers. An Important element is a variation on Note. A Caution is for information regarding possible data loss or software damage. A Warning is for information regarding possible hardware damage or injury to life or limb. <sgmltag>warning</sgmltag> Usage: Installing FreeBSD may make you want to delete Windows from your hard disk. ]]> Appearance: Installing FreeBSD may make you want to delete Windows from your hard disk. Lists and Procedures Information often needs to be presented as lists, or as a number of steps that must be carried out in order to accomplish a particular goal. To do this, use itemizedlist, orderedlist, or procedureThere are other types of list element in DocBook, but we are not concerned with those at the moment. itemizedlist and orderedlist are similar to their counterparts in HTML, ul and ol. Each one consists of one or more listitem elements, and each listitem contains one or more block elements. The listitem elements are analogous to HTML's li tags. However, unlike HTML, they are required. procedure is slightly different. It consists of steps, which may in turn consists of more steps or substeps. Each step contains block elements. <sgmltag>itemizedlist</sgmltag>, <sgmltag>orderedlist</sgmltag>, and <sgmltag>procedure</sgmltag> Usage: This is the first itemized item. This is the second itemized item. This is the first ordered item. This is the second ordered item. Do this. Then do this. And now do this. ]]> Appearance: This is the first itemized item. This is the second itemized item. This is the first ordered item. This is the second ordered item. Do this. Then do this. And now do this. Showing File Samples Fragments of a file (or perhaps a complete file) are shown by wrapping them in the programlisting element. White space and line breaks within programlisting are significant. In particular, this means that the opening tag should appear on the same line as the first line of the output, and the closing tag should appear on the same line as the last line of the output, otherwise spurious blank lines may be included. <sgmltag>programlisting</sgmltag> Usage: When finished, the program will look like this: #include <stdio.h> int main(void) { printf("hello, world\n"); }]]> Notice how the angle brackets in the #include line need to be referenced by their entities instead of being included literally. Appearance: When finished, the program will look like this: #include <stdio.h> int main(void) { printf("hello, world\n"); } Callouts A callout is a mechanism for referring back to an earlier piece of text or specific position within an earlier example without linking to it within the text. To do this, mark areas of interest in the example (programlisting, literallayout, or whatever) with the co element. Each element must have a unique id assigned to it. After the example include a calloutlist that refers back to the example and provides additional commentary. <sgmltag>co</sgmltag> and <sgmltag>calloutlist</sgmltag> When finished, the program will look like this: #include <stdio.h> int main(void) { printf("hello, world\n"); } Includes the standard IO header file. Specifies that main() returns an int. The printf() call that writes hello, world to standard output. ]]> Appearance: When finished, the program will look like this: #include <stdio.h> int main(void) { printf("hello, world\n"); } Includes the standard IO header file. Specifies that main() returns an int. The printf() call that writes hello, world to standard output. Tables Unlike HTML, DocBook does not need tables for layout purposes, as the stylesheet handles those issues. Instead, just use tables for marking up tabular data. In general terms (and see the DocBook documentation for more detail) a table (which can be either formal or informal) consists of a table element. This contains at least one tgroup element, which specifies (as an attribute) the number of columns in this table group. Within the tablegroup there is one thead element, which contains elements for the table headings (column headings), and one tbody which contains the body of the table. Both tgroup and thead contain row elements, which in turn contain entry elements. Each entry element specifies one cell in the table. <sgmltag>informaltable</sgmltag> Usage: This is Column Head 1 This is Column Head 2 Row 1, column 1 Row 1, column 2 Row 2, column 1 Row 2, column 2 ]]> Appearance: This is Column Head 1 This is Column Head 2 Row 1, column 1 Row 1, column 2 Row 2, column 1 Row 2, column 2 Always use the pgwide attribute with a value of 1 with the informaltable element. A bug in Internet Explorer can cause the table to render incorrectly if this is omitted. Table borders can be suppressed by setting the frame attribute to none in the informaltable element. For example, <informaltable frame="none">. Tables Where <literal>frame="none"</literal> Appearance: This is Column Head 1 This is Column Head 2 Row 1, column 1 Row 1, column 2 Row 2, column 1 Row 2, column 2 Examples for the User to Follow Examples for the user to follow are often necessary. Typically, these will consist of dialogs with the computer; the user types in a command, the user gets a response back, the user types another command, and so on. A number of distinct elements and entities come into play here. screen Everything the user sees in this example will be on the computer screen, so the next element is screen. Within screen, white space is significant. prompt, &prompt.root; and &prompt.user; Some of the things the user will be seeing on the screen are prompts from the computer (either from the operating system, command shell, or application). These should be marked up using prompt. As a special case, the two shell prompts for the normal user and the root user have been provided as entities. To indicate the user is at a shell prompt, use one of &prompt.root; and &prompt.user; as necessary. They do not need to be inside prompt. &prompt.root; and &prompt.user; are &os; extensions to DocBook, and are not part of the original DTD. userinput When displaying text that the user should type in, wrap it in userinput tags. It will be displayed differently than system output text. <sgmltag>screen</sgmltag>, <sgmltag>prompt</sgmltag>, and <sgmltag>userinput</sgmltag> Usage: &prompt.user; ls -1 foo1 foo2 foo3 &prompt.user; ls -1 | grep foo2 foo2 &prompt.user; su Password: &prompt.root; cat foo2 This is the file called 'foo2']]> Appearance: &prompt.user; ls -1 foo1 foo2 foo3 &prompt.user; ls -1 | grep foo2 foo2 &prompt.user; su Password: &prompt.root; cat foo2 This is the file called 'foo2' Even though we are displaying the contents of the file foo2, it is not marked up as programlisting. Reserve programlisting for showing fragments of files outside the context of user actions. In-line Elements Emphasizing Information To emphasize a particular word or phrase, use emphasis. This may be presented as italic, or bold, or might be spoken differently with a text-to-speech system. There is no way to change the presentation of the emphasis within the document, no equivalent of HTML's b and i. If the information being presented is important, then consider presenting it in important rather than emphasis. <sgmltag>emphasis</sgmltag> Usage: FreeBSD is without doubt the premiere Unix like operating system for the Intel architecture.]]> Appearance: FreeBSD is without doubt the premiere Unix like operating system for the Intel architecture. Quotations To quote text from another document or source, or to denote a phrase that is used figuratively, use quote. Most of the markup tags available for normal text are also available from within a quote. Quotations Usage: However, make sure that the search does not go beyond the boundary between local and public administration, as RFC 1535 calls it.]]> Appearance: However, make sure that the search does not go beyond the boundary between local and public administration, as RFC 1535 calls it. Keys, Mouse Buttons, and Combinations To refer to a specific key on the keyboard, use keycap. To refer to a mouse button, use mousebutton. And to refer to combinations of key presses or mouse clicks, wrap them all in keycombo. keycombo has an attribute called action, which may be one of click, double-click, other, press, seq, or simul. The last two values denote whether the keys or buttons should be pressed in sequence, or simultaneously. The stylesheets automatically add any connecting symbols, such as +, between the key names, when wrapped in keycombo. Keys, Mouse Buttons, and Combinations Usage: To switch to the second virtual terminal, press Alt F1. To exit vi without saving changes, type Esc: q!. My window manager is configured so that Alt right mouse button is used to move windows.]]> Appearance: To switch to the second virtual terminal, press Alt F1. To exit vi without saving changes, type Esc : q !. My window manager is configured so that Alt right mouse button is used to move windows. Applications, Commands, Options, and Cites Both applications and commands are frequently referred to when writing documentation. The distinction between them is that an application is the name of a program or suite of programs that fulfill a particular task. A command is the filename of a program that the user can type and run at a command line. It is often necessary to show some of the options that a command might take. Finally, it is often useful to list a command with its manual section number, in the command(number) format so common in Unix manuals. Mark up application names with application. To list a command with its manual section number (which should be most of the time) the DocBook element is citerefentry. This will contain a further two elements, refentrytitle and manvolnum. The content of refentrytitle is the name of the command, and the content of manvolnum is the manual page section. This can be cumbersome to write, and so a series of general entities have been created to make this easier. Each entity takes the form &man.manual-page.manual-section;. The file that contains these entities is in doc/share/xml/man-refs.ent, and can be referred to using this FPI: PUBLIC "-//FreeBSD//ENTITIES DocBook Manual Page Entities//EN" Therefore, the introduction to &os; documentation will usually include this: <!DOCTYPE book PUBLIC "-//FreeBSD//DTD DocBook V4.1-Based Extension//EN" [ <!ENTITY % man PUBLIC "-//FreeBSD//ENTITIES DocBook Manual Page Entities//EN"> %man; … ]> Use command when to include a command name in-line but present it as something the user should type in. Use option to mark up the options which will be passed to a command. When referring to the same command multiple times in close proximity, it is preferred to use the &man.command.section; notation to markup the first reference and use command to markup subsequent references. This makes the generated output, especially HTML, appear visually better. This can be confusing, and sometimes the choice is not always clear. Hopefully this example makes it clearer. Applications, Commands, and Options Usage: Sendmail is the most widely used Unix mail application. Sendmail includes the sendmail 8 , &man.mailq.1;, and &man.newaliases.1; programs. One of the command line parameters to sendmail 8 , , will display the current status of messages in the mail queue. Check this on the command line by running sendmail -bp.]]> Appearance: Sendmail is the most widely used Unix mail application. Sendmail includes the sendmail 8 , &man.mailq.1;, and &man.newaliases.1; programs. One of the command line parameters to sendmail 8 , , will display the current status of messages in the mail queue. Check this on the command line by running sendmail -bp. Notice how the &man.command.section; notation is easier to follow. Files, Directories, Extensions To refer to the name of a file, a directory, or a file extension, use filename. <sgmltag>filename</sgmltag> Usage: The XML source for the Handbook in English is found in /usr/doc/en_US.ISO8859-1/books/handbook/. The first file is called book.xml in that directory. There is also a Makefile and a number of files with a .ent extension.]]> Appearance: The XML source for the Handbook in English can be found in /usr/doc/en/handbook/. The first file is called handbook.xml in that directory. There is also a Makefile and a number of files with a .ent extension. The Name of Ports &os; Extension These elements are part of the &os; extension to DocBook, and do not exist in the original DocBook DTD. To include the name of a program from the &os; Ports Collection in the document, use the filename tag with the role attribute set to package. Since ports can be installed in any number of locations, only include the category and the port name; do not include /usr/ports. <sgmltag>filename</sgmltag> Tag with <literal>package</literal> Role Usage: Install the net/wireshark port to view network traffic.]]> Appearance: Install the net/wireshark port to view network traffic. Devices &os; Extension These elements are part of the &os; extension to DocBook, and do not exist in the original DocBook DTD. There are two names for devices: the device name as it appears in /dev, or the name of the device as it appears in the kernel. For this latter course, use devicename. Sometimes there is no choice. Some devices, such as network cards, do not have entries in /dev, or the entries are markedly different from their kernel device names. <sgmltag>devicename</sgmltag> Usage: sio is used for serial communication in FreeBSD. sio manifests through a number of entries in /dev, including /dev/ttyd0 and /dev/cuaa0. By contrast, network devices such as ed0 do not appear in /dev. In MS-DOS, the first floppy drive is referred to as a:. In FreeBSD it is /dev/fd0.]]> Appearance: sio is used for serial communication in FreeBSD. sio manifests through a number of entries in /dev, including /dev/ttyd0 and /dev/cuaa0. By contrast, network devices such as ed0 do not appear in /dev. In MS-DOS, the first floppy drive is referred to as a:. In FreeBSD it is /dev/fd0. Hosts, Domains, IP Addresses, and So Forth &os; Extension These elements are part of the &os; extension to DocBook, and do not exist in the original DocBook DTD. Identification information for networked computers (hosts) can be marked up in several ways, depending on the nature of the information. All of them use hostid as the element, with the role attribute selecting the type of the marked up information. No role attribute, or role="hostname" With no role attribute (i.e., hostid.../hostid) the marked up information is the simple hostname, such as freefall or wcarchive. The hostname can be explicitly specified with role="hostname". role="domainname" The text is a domain name, such as FreeBSD.org or ngo.org.uk. There is no hostname component. role="fqdn" The text is a Fully Qualified Domain Name, with both hostname and domain name parts. role="ipaddr" The text is an IP address, probably expressed as a dotted quad. role="ip6addr" The text is an IPv6 address. role="netmask" The text is a network mask, which might be expressed as a dotted quad, a hexadecimal string, or as a / followed by a number (CIDR notation). role="mac" The text is an Ethernet MAC address, expressed as a series of 2 digit hexadecimal numbers separated by colons. <sgmltag>hostid</sgmltag> and Roles Usage: The local machine can always be referred to by the name localhost, which will have the IP address 127.0.0.1. The FreeBSD.org domain contains a number of different hosts, including freefall.FreeBSD.org and bento.FreeBSD.org. When adding an IP alias to an interface (using ifconfig) always use a netmask of 255.255.255.255 (which can also be expressed as 0xffffffff). The MAC address uniquely identifies every network card in existence. A typical MAC address looks like 08:00:20:87:ef:d0.]]> Appearance: The local machine can always be referred to by the name localhost, which will have the IP address 127.0.0.1. The FreeBSD.org domain contains a number of different hosts, including freefall.FreeBSD.org and bento.FreeBSD.org. When adding an IP alias to an interface (using ifconfig) always use a netmask of 255.255.255.255 (which can also be expressed as 0xffffffff). The MAC address uniquely identifies every network card in existence. A typical MAC address looks like 08:00:20:87:ef:d0. Usernames &os; Extension These elements are part of the &os; extension to DocBook, and do not exist in the original DocBook DTD. To refer to a specific username, such as root or bin, use username. <sgmltag>username</sgmltag> Usage: To carry out most system administration functions requires logging in as root.]]> Appearance: To carry out most system administration functions requires logging in as root. Describing <filename>Makefile</filename>s &os; Extension These elements are part of the &os; extension to DocBook, and do not exist in the original DocBook DTD. Two elements exist to describe parts of Makefiles, maketarget and makevar. maketarget identifies a build target exported by a Makefile that can be given as a parameter to make. makevar identifies a variable that can be set (in the environment, on the make command line, or within the Makefile) to influence the process. <sgmltag>maketarget</sgmltag> and <sgmltag>makevar</sgmltag> Usage: Two common targets in a Makefile are all and clean. Typically, invoking all will rebuild the application, and invoking clean will remove the temporary files (.o for example) created by the build process. clean may be controlled by a number of variables, including CLOBBER and RECURSE.]]> Appearance: Two common targets in a Makefile are all and clean. Typically, invoking all will rebuild the application, and invoking clean will remove the temporary files (.o for example) created by the build process. clean may be controlled by a number of variables, including CLOBBER and RECURSE. Literal Text Literal text, or text which should be entered verbatim, is often needed in documentation. This is text that is excerpted from another file, or which should be copied exactly as shown from the documentation into another file. Some of the time, programlisting will be sufficient to denote this text. But programlisting is not always appropriate, particularly when you want to include a portion of a file in-line with the rest of the paragraph. On these occasions, use literal. <sgmltag>literal</sgmltag> Usage: The maxusers 10 line in the kernel configuration file determines the size of many system tables, and is a rough guide to how many simultaneous logins the system will support.]]> Appearance: The maxusers 10 line in the kernel configuration file determines the size of many system tables, and is a rough guide to how many simultaneous logins the system will support. Showing Items That the User <emphasis>Must</emphasis> Fill In There will often be times when the user is shown what to do, or referred to a file or command line, but cannot simply copy the example provided. Instead, they must supply some information themselves. replaceable is designed for this eventuality. Use it inside other elements to indicate parts of that element's content that the user must replace. <sgmltag>replaceable</sgmltag> Usage: &prompt.user; man command]]> Appearance: &prompt.user; man command replaceable can be used in many different elements, including literal. This example also shows that replaceable should only be wrapped around the content that the user is meant to provide. The other content should be left alone. Usage: The maxusers n line in the kernel configuration file determines the size of many system tables, and is a rough guide to how many simultaneous logins the system will support. For a desktop workstation, 32 is a good value for n.]]> Appearance: The maxusers n line in the kernel configuration file determines the size of many system tables, and is a rough guide to how many simultaneous logins the system will support. For a desktop workstation, 32 is a good value for n. Quoting System Errors System errors generated by &os; are marked with errorname. This indicates the exact error that appears. <sgmltag>errorname</sgmltag> Usage: Panic: cannot mount root]]> Appearance: Panic: cannot mount root Images Image support in the documentation is currently extremely experimental. The mechanisms described here are unlikely to change, but that is not guaranteed. Installation of the graphics/ImageMagick port is required. It is used to convert between the different image formats. This port is not in the textproc/docproj meta port, it must be installed by hand. The best example of what follows in practice is the doc/en_US.ISO8859-1/articles/vm-design/ document. If the description that follows is unclear, take a look at the files in that directory to see how everything hangs together. Experiment with creating different formatted versions of the document to see how the image markup appears in the formatted output. Image Formats Two image formats are currently supported. Which to choose will depend on the nature of the image. Images that are primarily vector based, such as network diagrams, time lines, and similar, should be in EPS (Encapsulated Postscript) format. These images have a .eps extension. For bitmaps, such as screen captures, use the PNG (Portable Network Graphic) format. These images have the .png extension. These are the only formats in which images should be committed to the Subversion repository. Use the appropriate format for each image. It is to be expected that documentation will have a mix of EPS and PNG images. The Makefiles ensure that the correct format image is chosen depending on the output format that you use for your documentation. Do not commit the same image to the repository in two different formats. It is anticipated that the Documentation Project will switch to using the SVG (Scalable Vector Graphic) format for vector images. However, the current state of SVG capable editing tools makes this impractical. Image Markup The markup for an image is relatively simple. First, markup a mediaobject. The mediaobject can contain other, more specific objects. We are concerned with two, the imageobject and the textobject. Include one imageobject, and two textobject elements. The imageobject will point to the name of the image file (without the extension). The textobject elements contain information that will be presented to the user as well as, or instead of, the image itself. There are two circumstances where this can happen. When the reader is viewing the documentation in HTML. In this case, each image will need associated alternate text to show the user, typically while the image is loading, or if they hover the mouse pointer over the image. When the reader is viewing the documentation in plain text. In this case, each image should have an ASCII art equivalent to show the user. An example will make things easier to understand. Suppose there is an image called fig1.png that is to be included in the document. This image is of a rectangle with an A inside it. The markup for this would be as follows. <mediaobject> <imageobject> <imagedata fileref="fig1"> </imageobject> <textobject> <literallayout class="monospaced">+---------------+ | A | +---------------+</literallayout> </textobject> <textobject> <phrase>A picture</phrase> </textobject> </mediaobject> Include an imagedata element inside the imageobject element. The fileref attribute should contain the filename of the image to include, without the extension. The stylesheets will work out which extension should be added to the filename automatically. The first textobject contains a literallayout element, where the class attribute is set to monospaced. This is an opportunity to demonstrate ASCII art skills. This content will be used if the document is converted to plain text. Notice how the first and last lines of the content of the literallayout element butt up next to the element's tags. This ensures no extraneous white space is included. The second textobject contains a single phrase element. The contents of this phrase will become the alt attribute for the image when this document is converted to HTML. Image <filename>Makefile</filename> Entries Images must be listed in the Makefile in the IMAGES variable. This variable must contain the names of all the source images. For example, if there are three figures, fig1.eps, fig2.png, fig3.png, then the Makefile should have lines like this in it. … IMAGES= fig1.eps fig2.png fig3.png … or … IMAGES= fig1.eps IMAGES+= fig2.png IMAGES+= fig3.png … Again, the Makefile will work out the complete list of images it needs to build the source document, you only need to list the image files you provided. Images and Chapters in Subdirectories Be careful when separating documentation into smaller files in different directories (see ). Suppose there is a book with three chapters, and the chapters are stored in their own directories, called chapter1/chapter.xml, chapter2/chapter.xml, and chapter3/chapter.xml. If each chapter has images associated with it, it is suggested to place those images in each chapter's subdirectory (chapter1/, chapter2/, and chapter3/). However, doing this requires including the directory names in the IMAGES variable in the Makefile, and including the directory name in the imagedata element in the document document. For example, if the book has chapter1/fig1.png, then chapter1/chapter.xml should contain: <mediaobject> <imageobject> <imagedata fileref="chapter1/fig1"> </imageobject> … </mediaobject> The directory name must be included in the fileref attribute. The Makefile must contain: … IMAGES= chapter1/fig1.png … Then everything will work. Links Links are also in-line elements. <literal>id</literal> Attributes Most DocBook elements accept an id attribute to give that part of the document a unique name. The id can be used as a target for a crossreference or link. Any portion of the document that will be a link target must have an id attribute. Assigning an id to all chapters and sections, even if there are no current plans to link to them, is a good idea. These ids can be used as unique anchor reference points by anyone referring to the HTML version of the document. <literal>id</literal> on Chapters and Sections Introduction This is the introduction. It contains a subsection, which is identified as well. More Details This is a subsection. ]]> Use descriptive values for id names. The values must be unique within the entire document, not just in a single file. In the example, the subsection id is constructed by appending text to the chapter id. This ensures that the ids are unique. It also helps both reader and anyone editing the document to see where the link is located within the document, similar to a directory path to a file. To allow the user to jump into a specific portion of the document, even in the middle of a paragraph or an example, use anchor. This element has no content, but takes an id attribute. <sgmltag>anchor</sgmltag> This paragraph has an embedded link target in it. It will not show up in the document.]]> Crossreferences with <literal>xref</literal> xref provides the reader with a link to jump to another section of the document. The target id is specified in the linkend attribute, and xref generates the link text automatically. Using <sgmltag>xref</sgmltag> Assume that this fragment appears somewhere in a document that includes the id example shown above: More information can be found in . More specific information can be found in .]]> The link text will be generated automatically, looking like (emphasized text indicates the link text):
More information can be found in Chapter 1, Introduction. More specific information can be found in Section 1.1, More Details.
The link text is generated automatically from the chapter and section number and title elements. xref cannot link to an id attribute on an anchor element. The anchor has no content, so the xref cannot generate the link text. Linking to the Same Document or Other Documents on the Web The link elements described here allow the writer to define the link text. It is very important to use descriptive link text to give the reader an idea of where the link will take them. Remember that DocBook can be rendered to multiple types of media. The reader may be looking at a printed book or other form of media where there are no links. If the link text is not descriptive enough, the reader may not be able to locate the linked section. Links to the Same Document link is used to create a link within the same document. The target id is specified in the linkend attribute. This element wraps content, which is used for the link text. Using <sgmltag>link</sgmltag> Assume that this fragment appears somewhere in a document that includes the id example. More information can be found in the sample introduction. More specific information can be found in the sample introduction with more details section.]]> This output will be generated (emphasized text is used to show the link text):
More information can be found in the sample introduction. More specific information can be found in the sample introduction with more details section.
link can be used to include links to the id of an anchor element, since the link content defines the link text. Linking to Other Documents on the Web The ulink is used to link to external documents on the web. The url attribute is the URL of the page that the link points to, and the content of the element is the text that will be displayed for the user to activate. <sgmltag>ulink</sgmltag> to a &os; Documentation Web Page Link to the book or article URL entity. To link to a specific chapter in a book, add a slash and the chapter file name, followed by an optional anchor within the chapter. For articles, link to the article URL entity, followed by an optional anchor within the article. URL entities can be found in doc/share/xml/urls.ent. Usage for book links: Read the SVN introduction, then pick the nearest mirror from the list of Subversion mirror sites.]]> Appearance: Read the SVN introduction, then pick the nearest mirror from the list of Subversion mirror sites. Usage for article links: Read this article about the BSD license, or just the introduction.]]> Appearance: Read this article about the BSD license, or just the introduction. <sgmltag>ulink</sgmltag> to a &os; Web Page Usage: Of course, you could stop reading this document and go to the FreeBSD home page instead.]]> Appearance: Of course, you could stop reading this document and go to the FreeBSD home page instead. <sgmltag>ulink</sgmltag> to an External Web Page Usage: Wikipedia has an excellent reference on GUID Partition Tables.]]> Appearance: Wikipedia has an excellent reference on GUID Partition Tables. + + The link text can be omitted to show the actual + URL: + + Wikipedia has an excellent reference on + GUID Partition Tables: .]]> + + Appearance: + + Wikipedia has an excellent reference on + GUID Partition Tables: .