In addition to its advanced document rendering features, Doxia also provides a macro engine that allows each input format to trigger injection of dynamic content. An excellent example of this is the snippet macro, which allows a document to pull a code snippet out of a source file that's available via HTTP. Using this macro, a small fragment of APT can be rendered into XHTML. The following APT code calls out to the snippet macro. Please note that this code should be on a single continuous line, the black slash character is inserted to denote a line break so that this code will fit on the printed page.

%{snippet|id=modello-model|url=http://svn.apache.org/repos/asf/maven/\
archetype/trunk/maven-archetype/maven-archetype-model/src/main/\
mdo/archetype.mdo}

<div class="source"><pre>

<model>
  <id>archetype</id>
  <name>Archetype</name>
  <description><![CDATA[Maven's model for the archetype descriptor.
  ]]></description>
  <defaults>
    <default>
      <key>package</key>
      <value>org.apache.maven.archetype.model</value>
    </default>
  </defaults>
  <classes>
    <class rootElement="true" xml.tagName="archetype">
      <name>ArchetypeModel</name>
      <description>Describes the assembly layout and packaging.</description>
      <version>1.0.0</version>
      <fields>
        <field>
          <name>id</name>
          <version>1.0.0</version>
          <required>true</required>
          <type>String</type>
        </field>
        ...
      </fields>
    </class>
  </classes>
</model>

</pre></div>

For more information about defining snippets in your code for reference by the snippet macro, see the Guide to the Snippet Macro on the Maven website, at http://maven.apache.org/guides/mini/guide-snippet-macro.html.