<?xml version="1.0" encoding="utf-8"?>  <!-- -*- nxml -*- -->
<!DOCTYPE article [
<!ENTITY version "5.0">
]>
<article xmlns="http://docbook.org/ns/docbook"
	 xmlns:xl="http://www.w3.org/1999/xlink"
	 version="5.0" xml:lang="en">
<info>
<title>DocBook V5.0</title>
<subtitle>The Transition Guide</subtitle>

<authorgroup>
<author><personname>Jirka Kosek</personname>
        <email>jirka@kosek.cz</email></author>
<author><personname>Norman Walsh</personname>
        <email>ndw@nwalsh.com</email>
        <contrib>§convert4to5, proofreading</contrib></author>
<author><personname>Dick Hamilton</personname>
        <email>rlhamilton@frii.com</email>
        <contrib>§changes-removed, customization, proofreading</contrib></author>
<othercredit
  class="other"
  otherclass="contributor"
  ><personname>Michael(tm) Smith</personname>
  <email>smith@sideshowbarker.net</email>
  <contrib>§dbxsl-ns</contrib>
</othercredit>
</authorgroup>

<pubdate>2008-02-06</pubdate>
<pubdate>2007-10-28</pubdate>
<pubdate>2006-10-22</pubdate>
<pubdate>2006-05-16</pubdate>
<pubdate>2006-03-01</pubdate>
<pubdate>2005-12-28</pubdate>
<pubdate>2005-10-27</pubdate>

</info>

<para>This document is targeted at DocBook users who are considering
switching from DocBook V4.x to DocBook V5.0. It describes
differences between DocBook V4.x and V5.0 and provides some suggestions about
how to edit and process DocBook V5.0 documents. There is
also a section devoted to conversion of legacy documents from DocBook
4.x to DocBook V5.0.</para>

<para>At the time this was written the current version of DocBook V5.0
was &version;. However, almost all of the information in this document is
general and applies to any newer version of DocBook V5.0.
</para>

<section xml:id="introduction">
<title>Introduction</title>

<para>The differences between DocBook V4.x and V5.0 are quite radical in
some aspects, but the basic idea behind DocBook is still the same, and
almost all element names are unchanged. Because of this it is very
easy to become familiar with DocBook V5.0 if you know any previous version of
DocBook. You can find a complete list of changes in
<citation>DB5SPEC</citation>, here we will discuss only the most
fundamental changes.</para>

<section xml:id="introduction-ns">
<title>Finally in a namespace</title>

<para>All DocBook V5.0 elements are in the namespace
<uri>http://docbook.org/ns/docbook</uri>. <acronym>XML<alt>Extensible
Markup Language</alt></acronym> namespaces are used to distinguish
between different element sets. In the last few years, almost all new
XML grammars have used their own namespace. It is easy to
create compound documents that contain elements from different XML
vocabularies. DocBook V5.0 is following this design rule. Using
namespaces in your documents is very easy. Consider this
simple article marked up in DocBook V4.5:</para>

<programlisting><![CDATA[<article>
  <title>Sample article</title>
  <para>This is a really short article.</para>
</article>]]></programlisting>

<para>The corresponding DocBook V5.0 article will look very similar:</para>

<programlisting><![CDATA[<article xmlns="http://docbook.org/ns/docbook" …>
  <title>Sample article</title>
  <para>This is a really short article.</para>
</article>]]></programlisting>

<para>The only change is the addition of a default namespace declaration
(<code>xmlns="http://docbook.org/ns/docbook"</code>) on the root
element. This declaration applies the namespace to the root element and
all nested elements. Each
element is now uniquely identified by its local name and namespace.</para>

<note>
<para>The namespace name <uri>http://docbook.org/ns/docbook</uri> serves
only as an identifier. This resource is not fetched during processing
of DocBook documents, and you are not required to have an Internet
connection during processing. If you access the namespace URI with a browser,
you will find a short explanatory document about the namespace. In the
future this document will probably conform to (some version of) RDDL
and provide pointers to related resources.</para>
</note>

</section>

<section xml:id="introduction-rng">
<title>Relaxing with DocBook</title>

<para>For more than a decade, the DocBook schema was defined using a
DTD. However, DTDs have serious limitations, and DocBook V5.0 is thus
defined using a very powerful schema language called RELAX NG. Thanks
to RELAX NG, it is now much easier to create customized versions of
DocBook, and some content models are now cleaner and more
precise.</para>

<para>Using RELAX NG has an impact on the document prolog. The following
example shows the typical prolog of a DocBook V4.x document. The version of
the DocBook DTD (in this case 4.5) is indicated in the document type
declaration (!DOCTYPE) which points to a particular version of the
DTD.</para>

<example xml:id="ex.docbook45">
<title>DocBook V4.5 document</title>
<programlisting><![CDATA[<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE article PUBLIC '-//OASIS//DTD DocBook XML V4.5//EN'
                         'http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd'>
<article lang="en">
  <title>Sample article</title>
  <para>This is a very short article.</para>
</article>]]></programlisting>
</example>

<para>In contrast, DocBook V5.0 does not depend on DTDs anymore. This
mean that there is no document type declaration and the version of DocBook
used is indicated with the <tag class="attribute">version</tag>
attribute instead.</para>

<example xml:id="ex.docbook5">
<title>DocBook V5.0 document</title>
<programlisting><![CDATA[<?xml version="1.0" encoding="utf-8"?>
<article xmlns="http://docbook.org/ns/docbook" version="5.0" xml:lang="en">
  <title>Sample article</title>
  <para>This is a very short article.</para>
</article>]]></programlisting>
</example>

<para>As you can see, DocBook V5.0 is built on top of existing XML
standards as much as possible, for example the <tag
class="attribute">lang</tag> attribute is superseded by the standard
<tag xl:href="http://www.w3.org/TR/REC-xml/#sec-lang-tag"
class="attribute">xml:lang</tag> attribute.</para>

<para>Another fundamental change is that there is no direct indication
of the schema used. Later in this document, you will learn how you can
specify a schema to be used for document validation.</para>

<note>
<para>Although we recommend the RELAX NG schema for DocBook
V5.0, there are also DTD and W3C XML Schema versions available (see <xref
linkend="schemas"/>) for tools that do not yet support RELAX NG.</para>
</note>

</section>

<section xml:id="introduction-why-to-switch">
<title>Why switch to DocBook V5.0?</title>

<para>The simple answer is <quote>because DocBook V5.0 is the
future</quote>. Apart from this marketing blurb, there are also more
technical reasons:</para>

<itemizedlist>
<listitem>
<para><emphasis>DocBook V4.x is feature frozen.</emphasis>DocBook V4.5
is the last version of DocBook in the V4.x series. Any new DocBook
development, like the addition of new elements, will be done in
DocBook V5.0. It is only matter of time before useful, new elements
will be added into DocBook V5.0, but they are not likely to be back
ported into DocBook V4.x. DocBook V4.x will be in maintenance mode and
errata will be published if necessary. </para>
</listitem>
<listitem>
<para><emphasis>DocBook V5.0 offers new functionality.</emphasis>
DocBook V5.0 provides significant improvements over DocBook V4.x. For
example there is general markup for annotations, a new and flexible
system for linking, and unified markup for information sections using
the <tag>info</tag> element.</para>
</listitem>
<listitem>
<para><emphasis>DocBook V5.0 is more extensible.</emphasis> Having
DocBook V5.0 in a separate namespace allows you to easily mix DocBook
markup with other XML-based languages like SVG, MathML, XHTML or even
FooBarML.</para>
</listitem>
<listitem>
<para><emphasis>DocBook V5.0 is easier to customize.</emphasis> RELAX
NG offers many powerful constructs that make customization much easier
than it would be using a DTD (see <xref linkend="customizations"/>).</para>
</listitem>
</itemizedlist>

</section>

<section xml:id="introduction-schemas">
<title>Schema jungle</title>

<para>Schemas for DocBook V5.0 are available in several formats at
<link xl:href="http://www.oasis-open.org/docbook/xml/&version;/"/> (or the
mirror at <link xl:href="http://docbook.org/xml/&version;/"/>).
Only the RELAX NG schema is normative
and it is preferred over the other schema languages.  However, for your
convenience there are also DTD and W3C XML Schema versions provided for DocBook
V5.0. But please note that neither the DTD nor the W3C XML schema are able to
capture all the constraints of DocBook V5.0. This mean that a
document that validates against the DTD or XML schema is not necessarily
valid against the RELAX NG schema and thus may not be a valid
DocBook V5.0 document.</para>

<para>DTD and W3C XML Schema versions of the DocBook V5.0 grammar are provided
as a convenience for users who want to use DocBook V5.0 with legacy tools
that don't support RELAX NG. Authors are encouraged to switch to RELAX
NG based tools as soon as possible, or at least to validate documents
against the RELAX NG schema before further processing.</para>

<para>Some document constraints can't be expressed in schema languages
like RELAX NG or W3C XML Schema. To check for these additional
constraints DocBook V5.0 uses Schematron.  We recommend that you
validate your document against both the RELAX NG and
Schematron schemas.</para>

<section xml:id="schemas">
<title>Where to get the schemas</title>

<para>The latest versions of schemas can be obtained from <link
xl:href="http://docbook.org/schemas/5x.html"/>. At the time this was
written the latest version was &version;. Individual schemas are
available at the following locations:</para>

<variablelist>
<varlistentry>
<term>RELAX NG schema</term>
<listitem><para><link xl:href="http://docbook.org/xml/&version;/rng/docbook.rng"/></para></listitem>
</varlistentry>
<varlistentry>
<term>RELAX NG schema in compact syntax</term>
<listitem><para><link xl:href="http://docbook.org/xml/&version;/rng/docbook.rnc"/></para></listitem>
</varlistentry>
<varlistentry>
<term>DTD</term>
<listitem><para><link xl:href="http://docbook.org/xml/&version;/dtd/docbook.dtd"/></para></listitem>
</varlistentry>
<varlistentry>
<term>W3C XML Schema</term>
<listitem><para><link xl:href="http://docbook.org/xml/&version;/xsd/docbook.xsd"/></para></listitem>
</varlistentry>
<varlistentry>
<term>Schematron schema with additional checks</term>
<listitem><para><link xl:href="http://docbook.org/xml/&version;/sch/docbook.sch"/></para></listitem>
</varlistentry>
</variablelist>

<para>These schemas are also available from the mirror at
<link xl:href="http://www.oasis-open.org/docbook/xml/&version;/"/>.</para>

</section>

<section xml:id="docs">
<title>DocBook documentation</title>

<para>Detailed documentation about each DocBook V5.0 element is
presented in <link
xl:href="http://docbook.org/tdg5/en/html/pt02.html">the reference part
of <citetitle>DocBook: The Definitive Guide</citetitle></link>.</para>

<note>
<para>Other parts of <citetitle>DocBook: The Definitive
Guide</citetitle> have not yet been updated to reflect the changes
made in DocBook V5.0. Please do not be confused by this.</para>
</note>

</section>

</section>

</section>

<section xml:id="tools">
<title>Tool chain</title>

<para>This section briefly describes tools and procedures to edit and
process content stored in DocBook V5.0.</para>

<section xml:id="editors">
<title>Editing DocBook V5.0</title>

<para>Because DocBook is an XML-based format and XML is a text-based
format, you can use any text editor to create and edit DocBook V5.0
documents. However, using <quote>dumb</quote> editors like Notepad is
not very productive. You will do better if you use an editor that
supports XML. Although there are DTD and W3C XML Schemas available for
DocBook V5.0, which means you can use any editor that works with DTDs
or W3C XML Schemas, we recommend that you use the RELAX NG grammar
with DocBook V5.0. The rest of this section contains an overview of
XML editors (listed in alphabetical order) that are known to work with
RELAX NG schemas and that offer guided editing based on the RELAX NG
schema.</para>

<section xml:id="editors-nxml">
<title>Emacs and nXML</title>

<para><link xl:href="http://www.thaiopensource.com/nxml-mode/">nXML
mode</link> is an add-on for the <application
xl:href="http://www.gnu.org/software/emacs/emacs.html">GNU
Emacs</application> text editor. By installing nXML you can turn Emacs
into a very powerful XML editor that offers guided editing and
validation of XML documents.</para>

<figure xml:id="f.emacs">
<title>Emacs with nXML mode provides guided editing and validation</title>
<mediaobject>
<imageobject role="html">
<imagedata fileref='images/emacs.png'/>
</imageobject>
<imageobject role="fo">
<imagedata fileref='images/emacs.png' width="100%"/>
</imageobject>
</mediaobject>
</figure>

<para>nXML uses a special configuration file named
<filename>schemas.xml</filename> to associate schemas with XML
documents. Often you will find this file in the directory
<filename>site-lisp/nxml/schema</filename> inside the Emacs installation
directory. Adding the following line into the configuration file,
will associate DocBook V5.0 elements with the appropriate
schema:</para>

<programlisting>&lt;namespace ns="http://docbook.org/ns/docbook" uri="<replaceable>/path/to/</replaceable>docbook.rnc"/></programlisting>

<note>
<para>Please note that nXML ships with a file named
<filename>docbook.rnc</filename>. This file contains the RELAX NG grammar
for DocBook V4.x. Be sure that you associate the DocBook V5.0 namespace
with the corresponding DocBook V5.0 grammar.</para>
</note>

<para>If you can't edit the global <filename>schemas.xml</filename> file,
you can create this file in the same directory as your document. nXML will
find associations placed there also. In this case you must create a
complete configuration file like:</para>

<programlisting>&lt;locatingRules xmlns="http://thaiopensource.com/ns/locating-rules/1.0">
  &lt;namespace ns="http://docbook.org/ns/docbook" uri="<replaceable>/path/to/</replaceable>docbook.rnc"/>
&lt;/locatingRules></programlisting>

</section>

<section xml:id="editors-oxygen">
<title>oXygen</title>

<para><application
xl:href="http://www.oxygenxml.com/">oXygen</application> is a feature
rich XML editor. It has built-in support for many schema languages
including RELAX NG. If you want to smoothly edit and validate DocBook
5.0 documents you should associate the DocBook namespace with the
corresponding schema. Go to
<menuchoice><guimenu>Options</guimenu><guisubmenu>Preferences…</guisubmenu><guisubmenu>Editor</guisubmenu><guimenuitem>Default
Schema Associations</guimenuitem></menuchoice>. Then click the
<guibutton>New</guibutton> button to add a new association. Type in
the DocBook namespace and the RELAX NG schema location, choose the
<guilabel>RNG Schema + Schematron</guilabel> type of schema as, and
confirm your choice by clicking the <guibutton>OK</guibutton>
button.</para>

<figure xml:id="f.oxygen">
<title>Adding a new schema association in oXygen</title>
<mediaobject>
<imageobject>
<imagedata fileref='images/oxygen1.png'/>
</imageobject>
</mediaobject>
</figure>

<para>Because oXygen comes with preconfigured associations for
DocBook V4.x, you must move your newly added configuration to the
top of the list (using the <guibutton>Up</guibutton> button).
That way you will be able to use
oXygen with both DocBook V4.x and DocBook V5.0.</para>

<figure xml:id="f.oxygen.assoc">
<title>DocBook V5.0 association must precede associations for DocBook V4.x</title>
<mediaobject>
<imageobject>
<imagedata fileref='images/oxygen2.png'/>
</imageobject>
</mediaobject>
</figure>

<para>Now you can close the preference box by clicking on the
<guibutton>OK</guibutton> button. oXygen will assist
you with writing DocBook V5.0 content, and you will be able to validate
your documents against both RELAX NG and Schematron schemas. </para>

<figure xml:id="f.oxygen.open5">
<title>DocBook V5.0 document opened in oXygen</title>
<mediaobject>
<imageobject>
<imagedata fileref='images/oxygen3.png' width="100%"/>
</imageobject>
</mediaobject>
</figure>

</section>

<section xml:id="editors-xxe">
<title>XML Mind XML editor</title>

<para><application xl:href="http://www.xmlmind.com/xmleditor/">XML
Mind XML editor</application> (XXE) is a visual validating XML editor that
provides a wordprocessor-like interface to users. It is available in
two versions, Standard and Professional. The Standard version is free and
provides everything you need to edit DocBook V5.0 documents.</para>

<figure xml:id="f.xmlmind">
<title>XML Mind XML Editor – feels almost like MS Word but real DocBook V5.0 markup is created</title>
<mediaobject>
<imageobject>
<imagedata fileref='images/xxe.png' width="100%"/>
</imageobject>
</mediaobject>
</figure>

<para>In order to use DocBook V5.0 in XXE you have to install
an add-on. Go to
<menuchoice><guimenu>Options</guimenu><guimenuitem>Install
Add-ons…</guimenuitem></menuchoice>. Then choose <guilabel>DocBook
5 configuration</guilabel> and press the <guibutton>OK</guibutton>
button. After restart, XXE is ready to work with DocBook V5.0
documents.</para>

</section>

</section>

<section xml:id="validators">
<title>Validating DocBook V5.0</title>

<para>If you are not using a RELAX NG-based validating editor when you
create documents, we strongly recommend that you validate your
documents against RELAX NG and Schematron schemas before processing
them. Only after successful validation can you be sure that your
document is really DocBook V5.0 and that processing tools will be able
to process it correctly.</para>

<para>For validation you can use tools that support simultaneous RELAX NG and
Schematron validation, or you can use NVDL to orchestrate validation using
the two schemas.</para>

<section xml:id="validators-rng-sch">
<title>Using RELAX NG and Schematron</title>

<para>You can find a list of RELAX NG validators at <link
xl:href="http://relaxng.org/#validators"/>. It is best to use
validators with support for embedded Schematron rules inside RELAX NG
schemas. Schematron is a rule-based validation language which is used
to impose additional constraints on DocBook documents. Schematron rules
assert conditions which are impossible or difficult to express 
in a pure RELAX NG schema.</para>

<para><application xl:href="https://msv.dev.java.net/">Sun 
Multi-Schema XML Validator (MSV)</application> is able to validate an XML
document against a RELAX NG schema and Schematron rules at the same time.
To install and use MSV follow these steps:</para>

<procedure>
<step>
<para>Download <filename>relames.zip</filename> from <link xl:href="https://msv.dev.java.net/servlets/ProjectDocumentList?folderID=101"/>.</para>
</step>
<step>
<para>Unpack the downloaded file into an arbitrary directory.</para>
</step>
<step>
<para>Validate your document using the following command:</para>
<screen><command>java</command> -Xss512K -jar <replaceable>/path/to/</replaceable>relames.jar <replaceable>/path/to/</replaceable>docbook.rng document.xml</screen>
<note>
<para>The switch <option>-Xss512K</option> increases the stack size
of the Java virtual machine. This is necessary because the DocBook schema is
quite large. If you get stack overflow errors from MSV, increase
this value. You may get spurious error messages if the value
is too small, so if you get a stack overflow error, ignore any other error
messages and try a larger value for the stack size.
If you are not using Sun's Java implementation, please consult the
documentation for your virtual machine to learn how to increase the stack
size.</para>
</note>
</step>
</procedure>

<para>There is also an <link
xl:href="http://relaxed.vse.cz/docbookvalidator/">on-line DocBook V5.0
validator</link> that validates DocBook V5.0 documents against the normative
RELAX NG schema with embedded Schematron rules.</para>

</section>

<section>
<title>Using NVDL</title>

<para>NVDL is a meta-schema language which can validate a document 
against several schemas. DocBook V5.0 comes with a NVDL
schema which specifies that DocBook documents should be validated
against both RELAX NG and Schematron schemas.</para>

<para>You can find a list of NVDL validators at <link
xl:href="http://nvdl.org/"/>. The following procedures show how to
install and use the <application
xl:href="http://www.oxygenxml.com/onvdl.html">oNVDL</application> and
<application xl:href="http://jnvdl.sourceforge.net">JNVDL</application>
validators.</para>

<procedure>
<title>oNVDL installation and usage</title>
<step>
<para>Download <filename
xl:href="http://www.oxygenxml.com/InstData/onvdl/onvdl-20070517.zip">onvdl-20070517.zip</filename>.</para>
</step>
<step>
<para>Unpack the downloaded file into an arbitrary directory.</para>
</step>
<step>
<para>Validate your document using the following command:</para>
<screen><command>java</command> -jar <replaceable>/path/to/oNVDL/</replaceable>bin/onvdl.jar <replaceable>/path/to/</replaceable>docbook.nvdl document.xml</screen>
</step>
</procedure>

<procedure>
<title>JNVDL installation and usage</title>
<step>
<para>Download the latest release of JNVDL from <link
xl:href="http://sourceforge.net/project/showfiles.php?group_id=164464"/>.</para>
</step>
<step>
<para>Unpack the downloaded file into an arbitrary directory.</para>
</step>
<step>
<para>Modify file <filename>jnvdl.bat</filename> (or <filename>jnvdl.sh</filename> on Unix based systems) to include <option>-Xss512K</option> switch directly after <command>java</command> command.</para>
</step>
<step>
<para>On Windows systems, validate your document using the following command:</para>
<screen><replaceable>/path/to/jnvdl/</replaceable><command>jnvdl</command> -nt -s <replaceable>/path/to/</replaceable>docbook.nvdl document.xml</screen>
<para>On Unix systems, validate your document using the following command:</para>
<screen><replaceable>/path/to/jnvdl/</replaceable><command>jnvdl.sh</command> -nt -s <replaceable>/path/to/</replaceable>docbook.nvdl document.xml</screen>
</step>
</procedure>

</section>

</section>

<section xml:id="processing">
<title>Processing DocBook V5.0</title>

<para>Part of DocBook's great success can be attributed to the
availability of free
tools that can be used to transform DocBook content into various
target formats including HTML and PDF. The DocBook XSL Stylesheets are
very popular tools.</para>

<section xml:id="dbxsl">
<title>DocBook XSL Stylesheets</title>

<para>The DocBook stylesheets are designed to process content written in
different versions of DocBook (for example 3.1 and 4.2). Recent
versions of the stylesheets are also able to process DocBook V5.0
with some limitations.</para>

<para>You can process DocBook V5.0 documents with the DocBook XSL
stylesheets in exactly the same way you process DocBook V4.x documents.
You do not need special software; you can stick to your preferred
XSLT processor, be it Saxon, xsltproc, Xalan or whatever else (but see
the note about the lost base URI below).</para>

<para>During document processing, the stylesheets strip
namespaces from DocBook V5.0 to get a document which will be
very similar to DocBook V4.x. This is necessary because from the XSLT
point of view, elements from different namespaces are distinct and cannot 
be easily processed by the same set of templates. This process is
completely transparent to the user. If you are processing DocBook V5.0
documents, the only difference is that you will see the following
additional message:</para>

<screen>Note: namesp. cut : stripped namespace before processing
Note: namesp. cut : processing stripped document</screen>

<para>Although you can successfully use the existing stylesheets to
process DocBook V5.0, there are some limitations and unsupported
features. The unsupported features include:</para>

<itemizedlist>
<listitem><para>general annotations;</para></listitem>
<listitem><para>general XLink links on all elements.</para></listitem>
</itemizedlist>

<note>
<para>During namespace stripping, the base URI of the document is
lost. This means that in rare situations, relatively referenced
resources like images or programlistings can be processed incorrectly.
The stylesheets attempt to compensate for this problem, but that is not always 
possible. When an XSLT processor other than Saxon or Xalan is used, a warning 
message is generated:

<screen>WARNING: cannot add @xml:base to node set root element. Relative paths may not work.</screen>
</para>

</note>
</section>

<section xml:id="dbxsl-ns">
<title>DocBook XSL-NS Stylesheets</title>
<para>As you can see from reading the previous section, namespace
  stripping has limitations that will cause trouble in some
  situations. To overcome those limitations, Bob Stayton created a
  build system for taking the non-namespace-aware DocBook XSL
  stylesheets and generating namespace-aware versions from them.
  The DocBook <link
    xl:href="http://docbook.sourceforge.net/release/xsl-ns/current/"
  >XSL-NS stylesheets</link> are the result.</para>

<para>The DocBook XSL-NS stylesheets are released side-by-side
  with the DocBook XSL stylesheets, as a separate <link
  xl:href="https://sourceforge.net/project/showfiles.php?group_id=21935&amp;package_id=219178"
  ><package>docbook-xsl-ns</package></link> package. They are the
recommended XSLT 1.0 stylesheets to use for transforming
namespaced (DocBook V5.0) documents.</para>
</section>

<section xml:id="dbxsl2">
<title>XSLT 2.0 based re-implementation</title>

<para>XSLT 1.0 is missing some important features. To work around
these missing features, the current DocBook XSL stylesheets use some
implementation-specific extensions.
XSLT 2.0 adds many new and previously missing features into the language.
A new set of DocBook stylesheets is being implemented based on XSLT 2.0
to take advantage of these features and to fully support DocBook V5.0.
</para>

<para>The XSLT 2.0 based stylesheets have many new features, including:</para>

<itemizedlist>
<listitem><para>seamless integration of profiling (conditional
documents) with external bibliographies and
glossaries;</para></listitem>
<listitem><para>no need for (most) external extensions;</para></listitem>
<listitem><para>internationalized indexes;</para></listitem>
<listitem><para>easy to customize titlepage templates.</para></listitem>
</itemizedlist>

<para>The XSLT 2.0 based stylesheets are still under development.  At
this writing, they only support HTML and chunked HTML output.  As time
permits, the stylesheet developers will be adding other formats.  Since
the stylesheets are developed in the limited free time the developers
have, there's no specific schedule.</para>

<para>There are not very many XSLT 2.0 implementations available.
But, if you want to try the new stylesheets, grab a snapshot of
the development version from <link
xl:href="http://docbook.sourceforge.net/snapshots/docbook-xsl2-snapshot.tar.bz2"/>
and unpack it somewhere. Then download and install Saxon 9 from <link
xl:href="http://saxon.sf.net"/>.</para>

<para>To transform a DocBook V5.0 document to a single HTML page use the command:</para>

<screen><command>java</command> -jar <replaceable>/path/to/</replaceable>saxon9.jar -o output.html document.xml <replaceable>/path/to/</replaceable>docbook-xsl2-snapshot/html/docbook.xsl</screen>

<para>To transform a DocBook V5.0 document to a set of chunked HTML pages use the command:</para>

<screen><command>java</command> -jar <replaceable>/path/to/</replaceable>saxon9.jar document.xml <replaceable>/path/to/</replaceable>docbook-xsl2-snapshot/html/chunk.xsl</screen>

</section>

</section>

</section>

<section xml:id="changes">
<title>Markup changes</title>

<para>This section describes the most common markup changes
between DocBook V4.x and V5.0.
You can find a complete list of changes in
<citation>DB5SPEC</citation>.</para>

<section xml:id="changes-linking">
<title>Improved cross-referencing and linking</title>

<para>In DocBook V4.x the attribute <tag class="attribute">id</tag> is
used to assign a unique identifier to an element. In DocBook V5.0 this
attribute is renamed <tag class="attribute">xml:id</tag> in order
to comply with <citation>XMLID</citation>.</para>

<para>Now you can use almost any inline element as the source of a link,
not just <tag>xref</tag> or <tag>link</tag>. For example, the following
DocBook 4.x content:</para> 

<programlisting><![CDATA[<section id="dir">
  <title>DIR command</title>
  <para>...</para>
</section>

<section id="ls">
  <title>LS command</title>
  <para>This command is a synonym for <link linkend="dir"><command>DIR</command></link> command.</para>
</section>]]></programlisting>

<para>is written in DocBook V5.0 as:</para>

<programlisting><![CDATA[<section xml:id="dir">
  <title>DIR command</title>
  <para>...</para>
</section>

<section xml:id="ls">
  <title>LS command</title>
  <para>This command is a synonym for <command linkend="dir">DIR</command> command.</para>
</section>]]></programlisting>

<para>The <tag class="attribute">linkend</tag> attribute was added to all
inline elements together with the <tag class="attribute">href</tag>
attribute from the XLink namespace. This means that you can use any inline
element as the source of a hypertext link. To use XLinks you have
to declare the XLink namespace (most often on the root element of your
document):</para>

<programlisting><![CDATA[<article xmlns="http://docbook.org/ns/docbook" 
         xmlns:xl="http://www.w3.org/1999/xlink" version="5.0">
  <title>Test article</title>

  <para><application xl:href="http://www.gnu.org/software/emacs/emacs.html">Emacs</application> 
    is my favourite text editor.</para>]]>
  …</programlisting>

<para>The <tag condition="v4">ulink</tag> element was removed from DocBook V5.0
in favor of XLink linking. Instead of the DocBook V4.x <tag condition="v4">ulink</tag>
element:</para>

<programlisting><![CDATA[<ulink url="http://docbook.org">DocBook site</ulink>]]></programlisting>

<para>you can now use <tag>link</tag></para>

<programlisting><![CDATA[<link xl:href="http://docbook.org">DocBook site</link>]]></programlisting>

<para>XLink links may contain a fragment identifier, which you can 
use instead of <tag class="attribute">linkend</tag> to form
cross-references inside a document; for example:</para>

<programlisting><![CDATA[<command xl:href="#dir">DIR</command>]]></programlisting>

<para>However XLink links are not checked during validation, while <tag
class="attribute">xml:id</tag>/<tag class="attribute">linkend</tag>
links are checked for ID/IDREF consistency.
One place where the XLink-based, fragment identifier scheme is
useful is when XInclude is being used, since XML ID/IDREF links
cannot span XInclude boundaries.
You can use whichever approach better suits your needs.</para>
</section>

<section xml:id="changes-renamed">
<title>Renamed elements</title>

<para>Some elements were renamed to better express their meaning or to
reduce the total number of elements available in DocBook.</para>

<table xml:id="t.renamed">
<title>Renamed elements</title>
<tgroup cols="2">
<thead>
<row>
<entry>Old name</entry>
<entry>New name</entry>
</row>
</thead>
<tbody>
<row>
<entry><tag condition="v4">sgmltag</tag></entry>
<entry><tag>tag</tag></entry>
</row>
<row>
<entry><tag condition="v4">bookinfo</tag>, <tag condition="v4">articleinfo</tag>,
<tag condition="v4">chapterinfo</tag>, <tag condition="nolink">*info</tag></entry>
<entry><tag>info</tag></entry>
</row>
<row>
<entry><tag condition="v4">authorblurb</tag></entry>
<entry><tag>personblurb</tag></entry>
</row>
<row>
<entry><tag condition="v4">collabname</tag>, <tag condition="v4">corpauthor</tag>,
<tag condition="v4">corpcredit</tag>, <tag condition="v4">corpname</tag></entry>
<entry><tag>orgname</tag></entry>
</row>
<row>
<entry><tag condition="v4">isbn</tag>, <tag condition="v4">issn</tag>,
<tag condition="v4">pubsnumber</tag></entry>
<entry><tag>biblioid</tag></entry>
</row>
<row>
<entry><tag condition="v4">lot</tag>, <tag condition="v4">lotentry</tag>, <tag condition="v4">tocback</tag>,
<tag condition="v4">tocchap</tag>, <tag condition="v4">tocfront</tag>, <tag condition="v4">toclevel1</tag>,
<tag condition="v4">toclevel2</tag>, <tag condition="v4">toclevel3</tag>, <tag condition="v4">toclevel4</tag>,
<tag condition="v4">toclevel5</tag>, <tag condition="v4">tocpart</tag></entry>
<entry><tag>tocdiv</tag></entry>
</row>
<row>
<entry><tag condition="v4">graphic</tag>, <tag condition="v4">graphicco</tag>,
<tag condition="v4">inlinegraphic</tag>, <tag condition="v4">mediaobjectco</tag></entry>
<entry><tag>mediaobject</tag> and <tag>inlinemediaobject</tag></entry>
</row>
<row>
<entry><tag condition="v4">ulink</tag></entry>
<entry><tag>link</tag></entry>
</row>
<row>
<entry><tag condition="v4">ackno</tag></entry>
<entry><tag>acknowledgements</tag></entry>
</row>
</tbody>
</tgroup>
</table>

</section>

<section xml:id="changes-removed">
<title>Removed elements</title>

<para>The following elements were removed from DocBook V5.0 without
direct replacements: <tag condition="v4">action</tag>, <tag
condition="v4">beginpage</tag>, <tag condition="v4">highlights</tag>,
<tag condition="v4">interface</tag>, <tag
condition="v4">invpartnumber</tag>, <tag
condition="v4">medialabel</tag>, <tag condition="v4">modespec</tag>,
<tag condition="v4">structfield</tag>, <tag
condition="v4">structname</tag>.
If you use one or more of these elements, here are some suggestions
as to how to re-code them in DocBook V5.0.
</para>

<table xml:id="t.removed">
<title>Recommended mapping for removed elements</title>
<tgroup cols="2">
<thead>
<row>
<entry>Old name</entry>
<entry>Recommended mapping</entry>
</row>
</thead>
<tbody>
<row>
<entry><tag condition="v4">action</tag></entry>
<entry>Use <computeroutput>&lt;<tag>phrase</tag> remap="action"&gt;</computeroutput>.</entry>
</row>
<row>
<entry><tag condition="v4">beginpage</tag></entry>
<entry>Remove: <tag condition="v4">beginpage</tag> is advisory only
and has tended to cause confusion.  A processing instruction or
comment should be a workable replacement if one is needed.</entry>
</row>
<row>
<entry><tag condition="v4">highlights</tag></entry>
<entry>Use <tag>abstract</tag>.  Note that because <tag
condition="v4">highlights</tag> has a broader content model, you may
need to wrap contents in a <tag>para</tag> inside
<tag>abstract</tag>.</entry>
</row>
<row>
<entry><tag condition="v4">interface</tag></entry>
<entry>Use one of the <quote>gui*</quote> elements
(<tag>guibutton</tag>, <tag>guiicon</tag>, <tag>guilabel</tag>,
<tag>guimenu</tag>, <tag>guimenuitem</tag>, or
<tag>guisubmenu</tag>).</entry>
</row>
<row>
<entry><tag condition="v4">invpartnumber</tag></entry>
<entry>Use <computeroutput>&lt;<tag>biblioid</tag> class="other"
otherclass="medialabel"&gt;</computeroutput>.  The
<tag>productnumber</tag> element is another alternative.</entry>
</row>
<row>
<entry><tag condition="v4">medialabel</tag></entry>
<entry>Use <computeroutput>&lt;<tag>citetitle</tag>
pubwork="<replaceable>mediatype</replaceable>"&gt;</computeroutput>,
where <replaceable>mediatype</replaceable> is the type of media being
labeled (e.g.,<tag class="attvalue">cdrom</tag> or <tag
class="attvalue">dvd</tag>).</entry>
</row>
<row>
<entry><tag condition="v4">modespec</tag></entry>
<entry>No longer needed.  The current processing model for
<tag>olink</tag> renders <tag condition="v4">modespec</tag>
unnecessary.</entry>
</row>
<row>
<entry><tag condition="v4">structfield</tag>, <tag condition="v4">structname</tag></entry>
<entry>Use <tag>varname</tag>. If you need to distinguish between the
two, use <computeroutput>&lt;<tag>varname</tag>
remap="<replaceable>structname or
structfield</replaceable>"&gt;</computeroutput>.  In some contexts, it
may also be appropriate to use <tag>property</tag> for <tag
condition="v4">structfield</tag>.</entry>
</row>
</tbody>
</tgroup>
</table>

</section>

</section>

<section xml:id="convert4to5">
<title>Converting DocBook V4.x documents to DocBook V5.0</title>

<para>The DocBook V5.0 schema ships with an XSLT 1.0 stylesheet that
is designed to transform valid DocBook V4.x documents to valid
DocBook V5.0 documents.</para>

<para>To convert your document, <filename>doc.xml</filename> in the
examples below, follow these steps:</para>

<procedure>
<step>
<para>Check the validity of your DocBook XML V4.x document. The
conversion tool assumes that the input document is valid. If the input
document contains markup errors, the results will be unpredictable at
best.</para>
</step>
<step>
<para>Transform <filename>doc.xml</filename> to
<filename>newdoc.xml</filename> with the
<filename>db4-upgrade.xsl</filename> stylesheet included in the
DocBook V5.0 distribution that you are using.</para>
</step>
<step>
<para>Check the validity of your DocBook XML V5.0 document against
the DocBook V5.0 RELAX NG grammar.</para>
</step>
</procedure>

<para>In the vast majority of cases, the resulting document should
be valid and your conversion process is finished.</para>

<para>If the document is not valid, please report the problem.
(Over time, we'll have more experience with the sorts of things
that can go wrong and we'll update this document to reflect that
experience.)</para>

<section xml:id="entities">
<title>What About Entities?</title>

<para>Using XSLT to transform existing documents to DocBook V5.0 has
one potential disadvantage: it removes all entity references from 
your document.</para>

<para>If preserving entities is an important aspect of your production
work flow, you will have to engage in a semi-manual process to
preserve them.</para>

<procedure>
<step>
<para>Open your existing document using your favorite editing tool.
You must use a tool that <emphasis>is not</emphasis> XML-aware, or one
that allows you to edit markup “in the raw”.</para>
</step>
<step>
<para>Replace all occurrences of the entity references that you want
to preserve with some unique string. For example, if you want to preserve
“<literal>&amp;Product;</literal>” references, you could replace them
all with “<literal>[[[Product]]]</literal>” (assuming that the string
“<literal>[[[Product]]]</literal>” doesn't occur anywhere else in your document).</para>
</step>
<step>
<para>Copy the document type declaration off of your document and save
it some place. The document type declaration is everything from
“<literal>&lt;!DOCTYPE</literal>” to the closing “<literal>]></literal>”.
</para>
</step>
<step>
<para>Perform the conversion described in <xref linkend="convert4to5"/>.
</para>
</step>
<step>
<para>Open the new document using your favorite editing tool. Replace
all occurrences of the unique string you used to save the entity references
with the corresponding entity references.</para>
</step>
<step>
<para>Paste the document type declaration that you saved onto the top
of your new document.</para>
</step>
<step>
<para>Remove the external identifier (the <literal>PUBLIC</literal>
and/or <literal>SYSTEM</literal> keywords) from the document type
declaration. A document that begins:</para>
<programlisting><![CDATA[<!DOCTYPE book [
<!ENTITY someEntity "some replacement text">
]>]]></programlisting>
<para>is perfectly well-formed. If you don't remove the references to
the DTD, then your parser will likely try to validate against DocBook
V4.0 and that's not going to work. Alternatively, you could refer
to the DocBook V5.0 DTD.</para>
</step>
</procedure>

<tip>
<para>Steps 2 and 5 from previous procedure can be automated using the
<link xl:href="http://docbook.svn.sourceforge.net/viewvc/docbook/trunk/contrib/tools/cloak">cloak
script</link> written by Michael Smith.</para>
</tip>

<section xml:id="extparsedentities">
<title>External Parsed Entities</title>

<para>External parsed entities, entities which load part of a document
from another file, are a special case. These can often be replaced
with XInclude elements.</para>

<para>The Perl script <filename>db4-entities.pl</filename>, also included
in the DocBook V5.0 distribution attempts to perform this replacement
for you. To use the script, perform the following steps:</para>

<procedure>
<step>
<para>Process your document with <filename>db4-entities.pl</filename>.
The script expects a single filename and prints the XInclude version
on standard output.</para>
</step>
<step>
<para>Process the XInclude version as described in <xref
linkend="convert4to5"/>.
</para>
</step>
</procedure>
</section>
</section>

</section>

<section xml:id="customizations">
  <title>Customizing DocBook V5.0</title>
  <!--
      ** RNG schema organization
      ** Removing attributes
      ** Adding new attributes
      ** Changing permitted content of attribute
      ** Removing elements
      ** Adding new elements
      ** Customizing content models
      ** Naming and versioning of DocBook customizations
  -->

  <para>
    It's much easier to customize DocBook V5.0 than it was to
    customize earlier releases.  This is partly because RELAX NG
    provides better support for modifications than DTDs and partly
    because the DocBook schema is designed to take full advantage
    of the capabilities RELAX NG provides.
    This section describes the organization of the RELAX NG schema for
    DocBook, methods and examples for adding, removing, and modifying elements
    and attributes, and conventions for naming and versioning
    DocBook customizations.
    It assumes some familiarity with RELAX NG.  If you are unfamiliar
    with RELAX NG, you can find a tutorial introduction in
    <citation>RNCTUT</citation>.
  </para>
  <section xml:id="relaxngorg">
    <title>DocBook RELAX NG schema organization</title>
    <para>
      The DocBook RELAX NG schema is highly modular, using named
      patterns extensively.  Every element, attribute, attribute
      list, and enumeration has its own named pattern.  In addition,
      there are named patterns for logical combinations of elements
      and attributes.  These named patterns provide <quote>hooks</quote>
      into the schema that allow you to do a wide range of customization
      by simply redefining one or more of the named patterns.
    </para>
    <para>
      An important design characteristic of the schema is that
      duplication is minimized.  This is done through the use of
      named patterns for common groupings that can be re-used.
      For example, the <tag>imagedata</tag> and <tag>videodata</tag>
      elements each have an <tag class="attribute">align</tag> attribute
      that takes the same set of enumerated values.  Rather than
      repeating those values, a single pattern,
      <varname>db.halign.enumeration</varname> is referenced by
      the <varname>db.videodata.align.enumeration</varname>
      and <varname>db.imagedata.align.enumeration</varname> patterns,
      which are in turn referenced by the
      <varname>db.videodata.align.attribute</varname>
      and <varname>db.imagedata.align.attribute</varname> patterns.
      While this may seem like overkill, it allows a customizer to modify
      the allowed enumerations for these two attributes separately or together,
      or to completely re-define the allowed content of either or both,
      by redefining one or more of these named patterns.
    </para>
    <section xml:id="patternnames"><title>Pattern Names</title>
    <para>
      Because named patterns are used extensively, the RELAX NG schema uses
      several naming conventions.  These are:
      <itemizedlist spacing="compact">
        <listitem>
          <para>
            Names have two or more parts, separated by dots <quote>.</quote>
          </para>
        </listitem>
        <listitem>
          <para>
            The first part of each name is the prefix <quote>db</quote>
          </para>
        </listitem>
        <listitem>
          <para>
            Each element has a named pattern in the form
            <varname>db.<replaceable>elementname</replaceable></varname>.
            Elements that have different content models in different
            contexts will also have patterns in the form
            <varname>db.<replaceable>context.elementname</replaceable></varname>.  For example, <varname>db.figure.info</varname>
            defines the content model for the <tag>info</tag> element
            when it appears as a child of the <tag>figure</tag> element.
            <replaceable>Context</replaceable> may have several parts.
            For example, <varname>db.cals.entrytbl.thead</varname>.
          </para>
        </listitem>
        <listitem>
          <para>
            Most attributes have a named pattern in the form
            <varname>db.<replaceable>attributename</replaceable>.attribute</varname>.
            Attributes that have different content models in different
            contexts will also have patterns in the form
            <varname>db.<replaceable>context.attributename</replaceable>.attribute</varname>.
            For example,
            <varname>db.olink.localinfo.attribute</varname> defines the content
            model of the <tag class="attribute">localinfo</tag> attribute when
            it appears in <tag>olink</tag>.
            There are a few attributes that do not have individual named
            patterns.  For example, the effectivity attributes are grouped
            into <varname>db.effectivity.attributes</varname> and not identified
            separately.
          </para>
        </listitem>
        <listitem>
          <para>
            Each element has a named pattern for its attribute list in
            the form
            <varname>db.<replaceable>elementname</replaceable>.attlist</varname>

            that defines the list of attributes for that element.
            Elements that have different attribute lists in different
            contexts will also have patterns in the form
            <varname>db.<replaceable>context.elementname</replaceable>.attlist</varname>
            For example, <varname>db.html.table.attlist</varname> defines
            the attribute list for the html <tag condition="nolink">table</tag> element and
            <varname>db.cals.table.attlist</varname> defines the attribute
            list for a cals <tag condition="nolink">table</tag> element.
          </para>
        </listitem>
        <listitem>
          <para>
            Each attribute that has enumerated values has a
            named pattern in the form
            <varname>db.<replaceable>[context.]attributename</replaceable>.enumeration</varname>.
            If the enumeration for a particular attribute depends on
            context, optional context is provided.
            For example,
            <varname>db.verbatim.continuation.enumeration</varname> defines
            the enumeration values for the
            <tag class="attribute">continuation</tag> attribute that is used
            in verbatim contexts like <tag>screen</tag>.
            Unlike elements and attributes, there is not necessarily a
            named pattern for enumerated attributes outside their context.
            For example, there is no <varname>db.class.enumeration</varname>
            because the <tag class="attribute">class</tag> attribute has
            a broad and non-intersecting range of uses.
          </para>
        </listitem>
        <listitem>
          <para>
            There are several different groupings of elements and attributes.
            Here are the major ones:
            <variablelist spacing="compact">
              <varlistentry>
                <term>inlines</term>
                <listitem>
                  <para>
                    Combinations of inline elements, for example,
                    <varname>db.error.inlines</varname>, which contains
                    <varname>db.errorcode</varname>,
                    <varname>db.errortext</varname>, etc.
                  </para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>blocks</term>
                <listitem>
                  <para>
                    Combinations of block elements, for example,
                    <varname>db.verbatim.blocks</varname>, which contains
                    <varname>db.programlisting</varname>,
                    <varname>db.screen</varname>, etc.
                  </para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>attributes</term>
                <listitem>
                  <para>
                    Combinations of attributes, for example,
                    <varname>db.effectivity.attributes</varname>,
                    which contains the attributes
                    <tag class="attribute">arch</tag>,
                    <tag class="attribute">condition</tag>,
                    <tag class="attribute">conformance</tag>, etc.
                  </para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>components</term>
                <listitem>
                  <para>
                    High level components of the schema, for example,
                    <varname>db.navigation.components</varname>, which contains
                    <varname>db.glossary</varname>,
                    <varname>db.bibliography</varname>,
                    <varname>db.index</varname>, and
                    <varname>db.toc</varname>, and is used inside the
                    content model for <tag>chapter</tag>, <tag>appendix</tag>,
                    and <tag>preface</tag>.
                  </para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>contentmodel</term>
                <listitem>
                  <para>
                    Shared content models, for example,
                    <varname>db.admonition.contentmodel</varname>, which contains
                    the content model for <tag>tip</tag>, <tag>warning</tag>,
                    <tag>note</tag>, etc.
                  </para>
                </listitem>
              </varlistentry>
            </variablelist>
          </para>
          <para>
            There are a couple of other groupings designed to minimize
            duplication, but these are the most important.
          </para>
        </listitem>
      </itemizedlist>
    </para>
  </section>
</section>
<section xml:id="customconsiderations">
  <title>General customization considerations</title>
  <para>
    Creating a customized schema is similar to
    creating a customization layer for XSL.  The schema customization
    layer is a new RELAX NG schema that defines your changes and
    includes the standard docbook schema.  You then validate using
    the schema customization as your schema.
  </para>
  <para>
    <xref linkend="ex-empty" xrefstyle="select: label"/> is an empty
    RELAX NG customization that does nothing
    except define the name spaces and include the standard DocBook schema.
    The <tag class="attribute">href</tag> attribute of the
    <tag condition="nolink">include</tag> element points to
    the location of the standard DocBook V5.0
    schema.<footnote><para>The examples in this section use
    <filename>docbook.rng</filename> as the schema location. If you want
    to create a portable schema customization you should use a standard
    web-accessible location like
    <uri>http://docbook.org/xml/&version;/rng/docbook.rng</uri> and
    then use <link
    xl:href="http://www.oasis-open.org/committees/download.php/14809/xml-catalogs.html">XML
    catalogs</link> to resolve this location to your local copy of the
    schema for improved performance. Unfortunately, at the time of
    this writing not all RELAX NG validators support XML catalogs.</para></footnote>
    All of the examples are given in both RNG and RNC form.
<example xml:id="ex-empty"><title>Empty customization file</title>
<programlisting language="rng"><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns:db="http://docbook.org/ns/docbook"
         ns="http://docbook.org/ns/docbook"
         xmlns="http://relaxng.org/ns/structure/1.0">
  <include href="docbook.rng"/>

  <!-- redefinitions of named patterns -->

</grammar>]]></programlisting>
<programlisting language="rnc"><![CDATA[namespace db = "http://docbook.org/ns/docbook"

include "docbook.rnc" inherit = db
# redefinitions of named patterns]]></programlisting>
</example>
  </para>
</section>
  <section xml:id="cust-elements">
    <title>Elements</title>
    <section xml:id="cust-add-elements">
      <title>Adding elements</title>
      <para>
        Adding an element typically takes two definitions.
        The first defines the new element and
        its content model, and the second adds the
        new element into the schema.  We'll show two examples.
      </para>
      <para>
        <xref linkend="ex-add-element-1"  xrefstyle="select: label"/>
        adds a new element,
        <tag condition="nolink">person</tag>, with the same
        content model as <tag>author</tag>.  The new element will be
        allowed to appear wherever <tag>author</tag> can appear.
      </para>
      <para>
        The <varname>db.author</varname> pattern is copied
        and renamed <varname>dbx.person</varname>, defining
        a new element called <tag condition="nolink">person</tag>.
        Then, the <varname>db.author</varname> pattern is redefined
        to be a choice of the current value or <varname>dbx.person</varname>.
        The <tag class="attribute">combine</tag> attribute tells
        RELAX NG to combine this pattern with the existing named
        pattern.  In this case, the value
        of the <tag class="attribute">combine</tag> attribute is
        <quote>choice</quote>, which tells the parser that either
        the original pattern or this new pattern is a valid match.
      </para>
<example xml:id="ex-add-element-1"><title>Adding a new element by duplicating an existing one</title>
<programlisting language="rng"><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns:db="http://docbook.org/ns/docbook"
         ns="http://docbook.org/ns/docbook"
         xmlns="http://relaxng.org/ns/structure/1.0">
  <include href="docbook.rng"/>
  <!-- define the new element -->
  <define name="dbx.person">
    <element name="person">
        <ref name="db.author.attlist"/>
        <ref name="db.credit.contentmodel"/>
    </element>
  </define>
  <!-- redefine the db.author pattern to allow db.person in
       the same places as db.author -->
  <define name="db.author" combine="choice">
    <ref name="dbx.person"/>
  </define>
</grammar>]]></programlisting>
<programlisting language="rnc"><![CDATA[default namespace db = "http://docbook.org/ns/docbook"

include "docbook.rnc"
# define the new element
dbx.person =
  element person { db.author.attlist, db.credit.contentmodel }
# redefine the db.author pattern to allow db.person in
# the same places as db.author
db.author |= dbx.person]]></programlisting>
</example>
    <para>
      The preceding method works well when you'd like a new element
      to be a clone or near-clone of an existing element.  It gives
      you complete control over the content model, but
      only limited control over where the element is allowed.  It
      works well when you want to allow the element in the same places
      as an existing element, and for this example that works
      nicely, since <tag>author</tag> is allowed in four different
      named patterns, each of which would have had to be redefined to
      allow <tag condition="nolink">person</tag>.
      But, if you can't find an existing element that is allowed in
      exactly the places you need, this method doesn't work as well.
    </para>
    <para>
      <xref linkend="ex-add-element-2" xrefstyle="select: label"/>
      adds two new elements by combining them into
      a higher level pattern.  In this example, we'll add
      two new inline elements for writing about assembly language,
      <tag condition="nolink">register</tag> and 
      <tag condition="nolink">instruction</tag>.
      We will allow them wherever programming inlines
      or operating system inlines are allowed.
      <xref linkend="ex-add-element-2" xrefstyle="select: label"/>
      defines the two elements, creates a new named pattern
      (<varname>dbx.asm.inlines</varname>) that contains them, and adds
      that pattern to <varname>db.programming.inlines</varname> and
      <varname>db.os.inlines</varname>.  Since these two patterns
      don't have any elements in common, the strategy used in 
      <xref linkend="ex-add-element-1" xrefstyle="select: label"/>
      would require selecting two different elements to <quote>clone</quote>,
      which would be messy.
    </para>
<example xml:id="ex-add-element-2"><title>Adding new inline elements</title>
<programlisting language="rng"><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns:db="http://docbook.org/ns/docbook"
         ns="http://docbook.org/ns/docbook"
         xmlns="http://relaxng.org/ns/structure/1.0">
  <include href="docbook.rng"/>
  <!-- define the new elements -->
  <define name="dbx.register">
    <element name="register">
      <text/>
    </element>
  </define>
  <define name="dbx.instruction">
    <element name="instruction">
      <text/>
    </element>
  </define>
  <!-- create a new pattern that contains the new inlines -->
  <define name="dbx.asm.inlines">
    <choice>
      <ref name="dbx.register"/>
      <ref name="dbx.instruction"/>
    </choice>
  </define>
  <!-- add the new inlines to programming and os inlines -->
    <define name="db.programming.inlines" combine="choice">
      <ref name="dbx.asm.inlines"/>
    </define>
    <define name="db.os.inlines" combine="choice">
      <ref name="dbx.asm.inlines"/>
    </define>
</grammar>]]></programlisting>
<programlisting language="rnc"><![CDATA[default namespace db = "http://docbook.org/ns/docbook"

include "docbook.rnc"
# define the new elements
dbx.register = element register { text }
dbx.instruction = element instruction { text }
# create a new pattern that contains the new inlines
dbx.asm.inlines = dbx.register | dbx.instruction
# add the new inlines to programming and os inlines
db.programming.inlines |= dbx.asm.inlines
db.os.inlines |= dbx.asm.inlines]]></programlisting>
</example>
    </section>
    <section xml:id="cust-delete-elements">
      <title>Deleting elements</title>
      <para>
        Deleting elements is straightforward, but takes some
        care and planning.  <xref linkend="ex-delete-element"
        xrefstyle="select: label"/> deletes
        the <tag>important</tag> admonition element by redefining
        it with a content model of <varname>notAllowed</varname>.
        Note that in this example, the redefinition is inside
        the <tag condition="nolink">include</tag> element.
        This is required for
        redefinitions that completely replace an existing pattern.
      </para>
      <para>
        Be careful; If you delete an element that is a required part
        of another element's content model, you can make it
        impossible to create a valid document.
        For example, if you delete the <tag>title</tag>
        element, you won't be able to validate a <tag>book</tag>
        because a <tag>book</tag> requires a <tag>title</tag>.
      </para>
<example xml:id="ex-delete-element"><title>Deleting an element</title>
<programlisting language="rng"><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns:db="http://docbook.org/ns/docbook"
         ns="http://docbook.org/ns/docbook"
         xmlns="http://relaxng.org/ns/structure/1.0">
  <include href="docbook.rng">
    <!-- redefine important element as notAllowed -->
    <define name="db.important">
      <notAllowed/>
    </define>
  </include>
</grammar>]]></programlisting>
<programlisting language="rnc"><![CDATA[namespace db = "http://docbook.org/ns/docbook"

include "docbook.rnc" inherit = db {
  # redefine important element as notAllowed
  db.important = notAllowed
}]]></programlisting>
</example>
    </section>
    <section xml:id="cust-modify-elements">
      <title>Customizing the content model of existing elements</title>
      <para>
         <xref linkend="ex-modify-element" xrefstyle="select: label"/>
         expands the definition of <tag>author</tag> to include two
         new elements, <tag condition="nolink">born</tag> and
         <tag condition="nolink">died</tag>.
         The <tag>author</tag> element allows two content models,
         <varname>db.person.author.contentmodel</varname>, which
         defines an author who is a person, and
         <varname>db.org.author.contentmodel</varname>, which
         defines an author that is an organization.  We will modify
         <varname>db.person.author.contentmodel</varname> so that
         only authors who are persons can have the new elements.
<example xml:id="ex-modify-element"><title>Modifying the content model of an element</title>
<programlisting language="rng"><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns:db="http://docbook.org/ns/docbook"
         ns="http://docbook.org/ns/docbook"
         xmlns="http://relaxng.org/ns/structure/1.0">
  <include href="docbook.rng"/>

  <define name="db.person.author.contentmodel" combine="interleave">
    <interleave>
      <optional>
        <element name="born">
          <ref name="db.date.contentmodel"/>
        </element>
      </optional>
      <optional>
        <element name="died">
          <ref name="db.date.contentmodel"/>
        </element>
      </optional>
    </interleave>
  </define>
</grammar>]]></programlisting>
<programlisting language="rnc"><![CDATA[default namespace = "http://docbook.org/ns/docbook"
namespace db = "http://docbook.org/ns/docbook"

include "docbook.rnc"

db.person.author.contentmodel &=
  element born { db.date.contentmodel }?
  & element died { db.date.contentmodel }?]]></programlisting>
</example>
      </para>
      <para>
        This modification will allow instances like this:
<programlisting><![CDATA[<author>
  <personname>Babe Ruth</personname>
  <born>02/06/1895</born>
  <died>08/16/1948</died>
</author>]]></programlisting>
but because we only modified the content model for authors
who are human, it won't allow an instance like this, which
uses <varname>db.org.author.contentmodel</varname>:
<programlisting><![CDATA[<!-- INVALID -->
<author>
  <orgname>Boston Red Sox</orgname>
  <died>1919</died>
  <born>2004</born>
</author>]]></programlisting>
      </para>
    </section>
  </section>
  <section xml:id="cust-attributes">
    <title>Attributes</title>
    <section xml:id="cust-add-attributes">
      <title>Adding attributes</title>
      <para>
        The simplest way to add an attribute to a single element
        is to add it to the attlist pattern for that element.
        <xref linkend="ex-add-attr" xrefstyle="select: label"/>
        adds the optional attributes <tag class="attribute">born</tag>
        and <tag class="attribute">died</tag> to the attribute
        list for <tag>author</tag>.
        The <varname>db.author.attlist</varname>
        named pattern is redefined with the
        <tag class="attribute">combine</tag> attribute set to
        <quote>interleave</quote>, which interleaves the two new
        optional attributes with the existing attributes on the list.
      </para>
<example xml:id="ex-add-attr"><title>Adding attributes</title>
<programlisting language="rng"><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns:db="http://docbook.org/ns/docbook"
         ns="http://docbook.org/ns/docbook"
         xmlns="http://relaxng.org/ns/structure/1.0">
  <include href="docbook.rng"/>

  <define name="db.author.attlist" combine="interleave">
    <interleave>
      <optional>
        <attribute name="born">
          <ref name="db.date.contentmodel"/>
        </attribute>
      </optional>
      <optional>
        <attribute name="died">
          <ref name="db.date.contentmodel"/>
        </attribute>
      </optional>
    </interleave>
  </define>
</grammar>]]></programlisting>
<programlisting language="rnc"><![CDATA[namespace db = "http://docbook.org/ns/docbook"

include "docbook.rnc" inherit = db

db.author.attlist &=
  attribute born { db.date.contentmodel }?
  & attribute died { db.date.contentmodel }?]]></programlisting>
</example>
    <para>
      Unlike
      <xref linkend="ex-modify-element" xrefstyle="select: label"/>,
      <xref linkend="ex-add-attr" xrefstyle="select: label"/> allows
      the new attributes to appear on any <tag>author</tag>
      element, not just those using the person content model.
    </para>
    <para>
      <xref linkend="ex-add-attr-2" xrefstyle="select: label"/> shows
      how you could limit the use of these attributes to authors who
      are persons.  In this example, the new attributes are interleaved
      with the <varname>db.person.author.contentmodel</varname>.  
      The only difference between this example and 
      <xref linkend="ex-modify-element" xrefstyle="select: label"/> is
      that the added patterns are identified as attributes rather than
      elements.  This shows some of the flexibility of RELAX NG, which
      treats attributes and elements very consistently.
<example xml:id="ex-add-attr-2"><title>Adding attributes; alternate method</title>
<programlisting language="rng"><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns:db="http://docbook.org/ns/docbook"
         ns="http://docbook.org/ns/docbook"
         xmlns="http://relaxng.org/ns/structure/1.0">
  <include href="docbook.rng"/>
  <!-- redefinitions of named patterns -->
  <define name="db.person.author.contentmodel" combine="interleave">
    <interleave>
      <optional>
        <attribute name="born">
          <ref name="db.date.contentmodel"/>
        </attribute>
      </optional>
      <optional>
        <attribute name="died">
          <ref name="db.date.contentmodel"/>
        </attribute>
      </optional>
    </interleave>
  </define>
</grammar>]]></programlisting>
<programlisting language="rnc"><![CDATA[namespace db = "http://docbook.org/ns/docbook"

include "docbook.rnc" inherit = db
# redefinitions of named patterns
db.person.author.contentmodel &=
  attribute born { db.date.contentmodel }?
  & attribute died { db.date.contentmodel }?]]></programlisting>
</example>
There is one difference in the treatment of attributes and elements
that is worth noting.  By the XML 1.0 definition, the relative order
of attributes is not significant.  Therefore, the
<tag condition="nolink">interleave</tag> block is not required for
attributes, though it does no harm.  
    </para>
    </section>
    <section xml:id="cust-delete-attributes">
      <title>Deleting attributes</title>
      <para>
        Deleting an attribute is similar to deleting an element,
        except that you use the RELAX NG <varname>empty</varname>
        pattern rather than <varname>notAllowed</varname>.
        <xref linkend="ex-delete-attr" xrefstyle="select: label"/>
        deletes the linking attributes, which are collected in the
        <varname>db.common.linking.attributes</varname> pattern,
        by defining that pattern as <varname>empty</varname>.
      </para>
<example xml:id="ex-delete-attr"><title>Deleting an attribute</title>
<programlisting language="rng"><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns:db="http://docbook.org/ns/docbook"
         ns="http://docbook.org/ns/docbook"
         xmlns="http://relaxng.org/ns/structure/1.0">
  <include href="docbook.rng">
    <define name="db.common.linking.attributes">
      <empty/>
    </define>
  </include>
</grammar>]]></programlisting>
<programlisting language="rnc"><![CDATA[namespace db = "http://docbook.org/ns/docbook"

include "docbook.rnc" inherit = db {
  db.common.linking.attributes = empty
}]]></programlisting>
</example>
      <para>
        Generally, <varname>empty</varname> is used when deleting
        attributes and <varname>notAllowed</varname> is used when
        deleting elements.
      </para>
    </section>
    <section xml:id="cust-modify-attributes">
      <title>Changing permitted content of attributes</title>
      <para>
        <xref linkend="ex-modify-attr" xrefstyle="select: label"/>
        modifies <varname>db.spacing.enumeration</varname> to
        add the additional value <quote>large</quote>.  Note
        that to remove a value from an enumeration, you need
        to redefine the entire enumeration, minus the values
        you don't need.
      </para>
<example xml:id="ex-modify-attr"><title>Deleting an attribute</title>
<programlisting language="rng"><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns:db="http://docbook.org/ns/docbook"
         ns="http://docbook.org/ns/docbook"
         xmlns="http://relaxng.org/ns/structure/1.0">
  <include href="docbook.rng"/>
  <!-- add value to an enumeration -->
  <define name="db.spacing.enumeration" combine="choice">
    <value>large</value>
  </define>
</grammar>]]></programlisting>
<programlisting language="rnc"><![CDATA[namespace db = "http://docbook.org/ns/docbook"

include "docbook.rnc" inherit = db
# add value to an enumeration
db.spacing.enumeration |= "large"]]></programlisting>
</example>
    </section>
  </section>

<section xml:id="cust-naming">
<title>Naming and versioning DocBook customizations</title>

<para>DocBook V5.0 is not tightly coupled with some particular
validation technology like DTDs. This also means that DocBook V5.0
documents don't have to (and usually don't) start with a
document type declaration (&lt;!DOCTYPE…>) to specify the schema
(DTD) to use. Instead, DocBook V5.0 instances can be easily
distinguished from other XML vocabularies by using elements in the
<uri>http://docbook.org/ns/docbook</uri> namespace. This namespace is
enough to distinguish DocBook from other XML based formats. But the
DocBook schema evolves over time and there are several versions of
DocBook (e.g. 3.1, 4.2, 4.5 and 5.0).  Since DocBook version 5.0, the
actual version used is indicated in the <tag
class="attribute">version</tag> attribute on a root element.</para>

<programlisting><![CDATA[<book xmlns="http://docbook.org/ns/docbook"
      version="5.0">
  …
</book>]]></programlisting>

<para>Future versions of DocBook documents will start with the same
markup, except the version number will be raised, for example to 5.1
or 6.0.
The namespace will remain the same until the semantics of the elements
change in a backward incompatible way, which is very unlikely to happen.</para>

<para>If you create a DocBook schema customization you must change the <tag
class="attribute">version</tag> attribute to distinguish your
customization from the <quote>official</quote> DocBook.  Changing the
namespace is not recommended because that would break the processing
tools.  Remember that changing namespaces is the same as renaming all
elements in the namespace.</para>

<para>When you customize the schema, use the following syntax to
identify your DocBook derivation:</para>

<programlisting><replaceable>base_version</replaceable>-[subset|extension|variant] [<replaceable>name</replaceable>[-<replaceable>version</replaceable>]?]+</programlisting>

<para>For example:</para>

<programlisting>5.0-subset simplified-1.0
5.0-variant ASMBook
5.0-variant ASMBook-2006
5.0-extension MathML-2.0 SVG-1.1</programlisting>

<para>The first part of the version identifier is the version number of the
DocBook schema from which you derived your customization.</para>

<para>If your schema is a proper subset, you can advertise this status
by using the <literal>subset</literal> keyword in the description. If
your schema contains any markup model extensions, you can advertise
this status by using the <literal>extension</literal> keyword. If
you'd rather not characterize your variant specifically as a subset or
an extension, use the <literal>variant</literal> keyword.</para>

<para>After these keywords you may add a whitespace separated list of
customization identifiers. Each name may be optionally followed by its
version number.</para>

</section>

</section>

<section xml:id="faq">
<title>FAQ</title>

<qandaset>
<qandadiv>
<title>Authoring</title>

<qandaentry xml:id="faq-authoring-schema-association">
<question>
<para>How do I attach a schema to a DocBook V5.0 document when I do not
want to use DTDs and !DOCTYPE?</para>
</question>
<answer>
<para>There is no standard way of associating a RELAX NG schema with a
document. Most tools provide some mechanism for performing this
association, consult the documentation for your application. In some
tools you must specify schema manually each time you want to
edit/process your document.</para>
</answer>
</qandaentry>

<qandaentry xml:id="faq-authoring-general-entities">
<question>
<para>How do I use entities like <tag class="genentity">ndash</tag> in
DocBook V5.0?</para>
</question>
<answer>
<para>Modern schema languages (including RELAX NG and W3X XML Schema)
do not provide any means to define entities that can be used for easier
typing of special characters. Some editors provide functions or
special toolbars that allow you to easily pick necessary character
and insert it into document as a raw Unicode character or a numeric
character reference.</para>
<para>Another possibility is to include entity definitions in the
prolog of your document. <link
xl:href="http://www.w3.org/2003/entities/">Entity definition
files</link> are now maintained by W3C. You can reference definition
files with entity definitions you are interested in and then reference
imported entities. For example:</para>
<programlisting><![CDATA[<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE article [
<!ENTITY % isopub SYSTEM "http://www.w3.org/2003/entities/iso8879/isopub.ent">
%isopub;
]>
<article xmlns="http://docbook.org/ns/docbook" version="5.0">
<title>DocBook V5.0 &ndash; the superb documentation format</title>]]>
…</programlisting>
<para>For your convenience there is also flattened entity definition
file which contains all entity definitions.</para>
<programlisting><![CDATA[<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE article [
<!ENTITY % allent SYSTEM "http://www.w3.org/2003/entities/2007/w3centities-f.ent">
%allent;
]>
<article xmlns="http://docbook.org/ns/docbook" version="5.0">
<title>DocBook V5.0 &ndash; the superb documentation format</title>]]>
…</programlisting>
</answer>
</qandaentry>

<qandaentry xml:id="faq-authoring-modularization">
<question>
<para>How to modularize documents?</para>
</question>
<answer>
<para>You can use <link
xl:href="http://www.w3.org/TR/xinclude/">XInclude</link> for this
task. There is an alternative schema for DocBook V5.0 that
contains XInclude elements. This is necessary to make some XML editors
happy. This schema can be found in files that end with letters <quote>xi</quote>, e.g.
<filename>docbookxi.rnc</filename> instead of
<filename>docbook.rnc</filename>.</para>
</answer>
</qandaentry>

<qandaentry xml:id="faq-authoring-validating-xincludes">
<question>
<para>How to validate documents which are composed by XInclude?</para>
</question>
<answer>
<para>If you are using XIncludes you should make sure that the final
document after resolving all inclusions is valid DocBook V5.0
instance. This means that all XIncludes should be processed before
validation takes place. The following command can be used to enable
XInclude processing in oNVDL.</para>
<screen><command>java</command> -Dorg.apache.xerces.xni.parser.XMLParserConfiguration=org.apache.xerces.parsers.XIncludeParserConfiguration -jar <replaceable>/path/to/oNVDL/</replaceable>bin/onvdl.jar <replaceable>/path/to/</replaceable>docbook.nvdl document.xml</screen>
<para>For JNVDL you can use switch <option>-xi</option> to enable XInclude processing.</para>
</answer>
</qandaentry>

</qandadiv>

<qandadiv>
<title>Stylesheets</title>

<qandaentry xml:id="faq-stylesheets-future">
<question>
<para>Will the current DocBook XSL stylesheets (XSLT 1.0 based
implementation) be maintained and improved in the future since work on
a new XSLT 2.0 based implementation has started?</para>
</question>
<answer>
<para>Yes, the current stylesheets (like 1.73.x) will be supported and
improved further because they are very widely deployed and work with
many existing XSLT processors.</para>
<para>Surely there will be a point in a future when all new development
will be switched to the XSLT 2.0 based implementation. But this
will not happen until all features of the current stylesheets are
implemented in the new stylesheets, and until there is more than
one usable XSLT 2.0 processor available.</para>
</answer>
</qandaentry>

</qandadiv>

<qandadiv>
<title>Schema customizations</title>

<qandaentry xml:id="faq-customization-mathml">
<question>
<para>How can I extend the DocBook schema with MathML elements?</para>
</question>
<answer>
<para>The basic DocBook schema allows elements from the MathML namespace
to appear inside the <tag>equation</tag> element.  This means that you can
validate a DocBook+MathML document, but MathML content will be ignored
during the validation. You will also not be able to use guided editing
for the MathML content.</para>
<para>If you need strict validation of MathML content or guided
editing for MathML, you can easily extend the base DocBook schema with
the MathML schema.</para>
<procedure>
<title>Extending the DocBook schema with the MathML schema</title>
<step>
<para>Download the MathML RELAX NG schema from <link
xl:href="http://yupotan.sppd.ne.jp/relax-ng/mml2.html"/> and unpack it
somewhere (e.g. into a <filename>mathml</filename> subdirectory).</para>
</step>
<step>
<para>Create a schema customization in compact syntax—<filename>dbmathml.rnc</filename>:</para>
<programlisting language="rnc">namespace html = "http://www.w3.org/1999/xhtml"
namespace mml = "http://www.w3.org/1998/Math/MathML"
namespace db = "http://docbook.org/ns/docbook"

include "/path/to/docbook.rnc" {
  db._any.mml = external "mathml/mathml2.rnc"
  db._any =
    element * - (db:* | html:* | mml:*) {
      (attribute * { text }
       | text
       | db._any)*
    }
}</programlisting>
<para>Or, alternatively, you can use the XML syntax of RELAX NG—<filename>dbmathml.rng</filename>:</para>
<programlisting language="rng"><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0">

<include href="/path/to/docbook.rng">
  <define name="db._any.mml">
    <externalRef href="mathml/mathml2.rng"/>
  </define>

  <define name="db._any">
    <element>
      <anyName>
        <except>
          <nsName ns="http://docbook.org/ns/docbook"/>
          <nsName ns="http://www.w3.org/1999/xhtml"/>
          <nsName ns="http://www.w3.org/1998/Math/MathML"/>
        </except>
      </anyName>
      <zeroOrMore>
        <choice>
          <attribute>
            <anyName/>
          </attribute>
          <text/>
          <ref name="db._any"/>
        </choice>
      </zeroOrMore>
    </element>
  </define>
</include>

</grammar>]]></programlisting>
</step>
<step>
<para>Now use the customized schema (<filename>dbmathml.rnc</filename>
or <filename>dbmathml.rng</filename>) instead of the original
DocBook schema.</para>
</step>
</procedure>
</answer>
</qandaentry>

<qandaentry xml:id="faq-customization-svg">
<question>
<para>How can I extend the DocBook schema with SVG elements?</para>
</question>
<answer>
<para>The situation is the same as with MathML support. You can use
elements from the SVG namespace inside the <tag>imageobject</tag>
element.</para>
<procedure>
<title>Extending the DocBook schema with the SVG schema</title>
<step>
<para>Download the SVG RELAX NG schema from <link
xl:href="http://www.w3.org/Graphics/SVG/1.1/rng/rng.zip"/> and unpack it
somewhere (e.g. into an <filename>svg</filename> subdirectory).</para>
</step>
<step>
<para>Create a schema customization in compact syntax—<filename>dbsvg.rnc</filename>:</para>
<programlisting language="rnc">namespace html = "http://www.w3.org/1999/xhtml"
namespace db = "http://docbook.org/ns/docbook"
namespace svg = "http://www.w3.org/2000/svg"

include "/path/to/docbook.rnc" {
  db._any.svg = external "svg/svg11.rnc"
  db._any =
    element * - (db:* | html:* | svg:*) {
      (attribute * { text }
       | text
       | db._any)*
    }
}</programlisting>
<para>Or, alternatively, you can use the XML syntax of RELAX NG—<filename>dbsvg.rng</filename>:</para>
<programlisting language="rng"><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0">

<include href="/path/to/docbook.rng">
  <define name="db._any.svg">
    <externalRef href="svg/svg11.rng"/>
  </define>

  <define name="db._any">
    <element>
      <anyName>
        <except>
          <nsName ns="http://docbook.org/ns/docbook"/>
          <nsName ns="http://www.w3.org/1999/xhtml"/>
          <nsName ns="http://www.w3.org/2000/svg"/>
        </except>
      </anyName>
      <zeroOrMore>
        <choice>
          <attribute>
            <anyName/>
          </attribute>
          <text/>
          <ref name="db._any"/>
        </choice>
      </zeroOrMore>
    </element>
  </define>
</include>

</grammar>]]></programlisting>
</step>
<step>
<para>Now use the customized schema (<filename>dbsvg.rnc</filename>
or <filename>dbsvg.rng</filename>) instead of the original
DocBook schema.</para>
</step>
</procedure>
</answer>
</qandaentry>

<qandaentry xml:id="faq-customization-mathml-svg">
<question>
<para>Is it possible to use the previous two customizations for MathML
and SVG together?</para>
</question>
<answer>
<para>Yes, you can create a special schema customization that combines
both MathML and SVG with the DocBook schema. In compact syntax, the merged
schema is:</para>
<programlisting language="rnc">namespace html = "http://www.w3.org/1999/xhtml"
namespace mml = "http://www.w3.org/1998/Math/MathML"
namespace db = "http://docbook.org/ns/docbook"
namespace svg = "http://www.w3.org/2000/svg"

include "/path/to/docbook.rnc" {
  db._any.mml = external "mahtml/mathml2.rnc"
  db._any.svg = external "svg/svg11.rnc"
  db._any =
    element * - (db:* | html:* | mml:* | svg:*) {
      (attribute * { text }
       | text
       | db._any)*
    }
}</programlisting>
<para>Or alternatively in the full RELAX NG syntax:</para>
<programlisting language="rng"><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0">

<include href="/path/to/docbook.rng">
  <define name="db._any.mml">
    <externalRef href="mathml/mathml2.rng"/>
  </define>

  <define name="db._any.svg">
    <externalRef href="svg/svg11.rng"/>
  </define>

  <define name="db._any">
    <element>
      <anyName>
        <except>
          <nsName ns="http://docbook.org/ns/docbook"/>
          <nsName ns="http://www.w3.org/1999/xhtml"/>
          <nsName ns="http://www.w3.org/1998/Math/MathML"/>
          <nsName ns="http://www.w3.org/2000/svg"/>
        </except>
      </anyName>
      <zeroOrMore>
        <choice>
          <attribute>
            <anyName/>
          </attribute>
          <text/>
          <ref name="db._any"/>
        </choice>
      </zeroOrMore>
    </element>
  </define>
</include>

</grammar>]]></programlisting>
</answer>
</qandaentry>

<qandaentry xml:id="faq-customization-links">
<question>
<para>Are there any other examples of schema customization
available?</para>
</question>
<answer>
<para>Sure. Some of the are listed bellow:</para>
<itemizedlist>
<listitem><para><link
xl:href="http://www.w3.org/TR/xml-i18n-bp/#docbook-plus-its">Sample
customization of ITS and DocBook</link></para></listitem>
<listitem><para><link
xl:href="http://wiki.docbook.org/topic/DocbookSchemas">Examples on
DocBook WiKi</link></para></listitem>
</itemizedlist>
</answer>
</qandaentry>

</qandadiv>

<qandadiv>
<title>Tool specific problems</title>

<qandaentry xml:id="faq-tools-xmlspy-xmlid">
<question>
<para>I'm using Altova XMLSpy to validate DocBook V5.0 instances
against the W3C XML Schema (<filename>docbook.xsd</filename>). XMLSpy
complains about undefined <tag class="attribute">xml:id</tag>
attributes?</para>
</question>
<answer>
<para>XMLSpy always uses its own bundled version of
<filename>xml.xsd</filename> which unfortunately doesn't define the <tag
class="attribute">xml:id</tag> attribute. The bundled version of
<filename>xml.xsd</filename> is hardwired into the program and cannot
be replaced by a newer version. To solve this problem you must upgrade
to version 2006 SP1.</para>
</answer>
</qandaentry>

</qandadiv>

</qandaset>
</section>

<bibliography xml:id="references">

<bibliomixed>
<abbrev>RNCTUT</abbrev>
Clark, James – Cowan, John – MURATA, Makoto: <title>RELAX NG Compact Syntax Tutorial</title>.
Working Draft, 26 March 2003. OASIS. <bibliomisc><link xl:href="http://relaxng.org/compact-tutorial-20030326.html"/></bibliomisc>
</bibliomixed>

<bibliomixed>
<abbrev>NVDLTUT</abbrev>
Nálevka, Petr:
<title>NVDL Tutorial</title>.
<bibliomisc><link xl:href="http://jnvdl.sourceforge.net/tutorial.html"/></bibliomisc>
</bibliomixed>

<bibliomixed>
<abbrev>XMLID</abbrev>
Marsh, Jonathan – 
Veillard, Daniel –
Walsh, Norman: <title>xml:id Version 1.0</title>. W3C Recommendation, 9 September 2005. <bibliomisc><link xl:href="http://www.w3.org/TR/xml-id/"/></bibliomisc>
</bibliomixed>

<bibliomixed>
<abbrev>DB5SPEC</abbrev>
Norman, Walsh: <title>The DocBook Schema</title>.
Working Draft 5.0a1, OASIS, 29 June 2005.
<bibliomisc><link xl:href="http://www.docbook.org/specs/wd-docbook-docbook-5.0a1.html"/></bibliomisc>
</bibliomixed>

</bibliography>

</article>