Example: Aggregating constraint and expansion modules using RNG

This section is non-normative.

The DITA architect wants to add some extension modules to the document-type shell for topic. The document-type shell already integrates a constraint module.

The following table lists the constraint module and the extension modules that the DITA architect wants to integrate into the document-type shell for topic.

Type of element configuration	File name	What it does
Constraint	topicSectionConstraint.rng	Constrains <topic>: Removes <abstract> Makes <shortdesc> required Removes <related-links> Disallows topic nesting Constrains <section>: Makes @id required
Expansion	sectionExpansionMod.rng	Adds <sectionDesc> to the content model of <section>
Expansion	tableCellAttExpansion.rng	Adds @cellPurpose to the attribute lists for certain table elements

Because all of these element-configuration modules target elements declared in topicMod.rng, the DITA architect needs to combine them into a single element-configuration module like the following:

<?xml version="1.0" encoding="UTF-8"?>
<?xml-model href="urn:pubid:oasis:names:tc:dita:rng:vocabularyModuleDesc.rng"
                         schematypens="http://relaxng.org/ns/structure/1.0"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0"
  xmlns:dita="http://dita.oasis-open.org/architecture/2005/"
  xmlns:a="http://relaxng.org/ns/compatibility/annotations/1.0"
  datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
  <div>
    <a:documentation>CONTENT MODEL AND ATTRIBUTE LIST OVERRIDES</a:documentation>
    <include href="urn:pubid:oasis:names:tc:dita:rng:topicMod.rng:2.0">
      <!-- Redefines attribute list for section: Makes @id required -->
      <define name="section.attributes">
        <attribute name="id">
          <data type="ID"/>
        </attribute>
        <ref name="conref-atts"/>
        <ref name="select-atts"/>
        <ref name="localization-atts"/>
        <optional>
          <attribute name="outputclass"/>
        </optional>
      </define>
      <!-- Adds sectionDesc to the content model of section -->
      <define name="section.content">
        <optional>
          <ref name="title"/>
        </optional>
        <optional>
          <ref name="sectionDesc"/>
        </optional>
        <zeroOrMore>
          <ref name="section.cnt"/>
        </zeroOrMore>
      </define>
      <!-- Adds @cellPurpose to certain table and simple table elements -->
      <define name="colspec.attributes" combine="interleave">
        <optional>
          <attribute name="cellPurpose"/>
        </optional>
      </define>
      <define name="entry.attributes" combine="interleave">
        <optional>
          <attribute name="cellPurpose"/>
        </optional>
      </define>
      <define name="row.attributes" combine="interleave">
        <optional>
          <attribute name="cellPurpose"/>
        </optional>
      </define>
      <define name="stentry.attributes" combine="interleave">
        <optional>
          <attribute name="cellPurpose"/>
        </optional>
      </define>
      <define name="strow.attributes" combine="interleave">
        <optional>
          <attribute name="cellPurpose"/>
        </optional>
      </define>
      <!-- Redefines topic: removes abstract and related-links; makes shortdesc -->
      <!--                  required; disallows topic nesting                   -->
      <define name="topic.content">
        <ref name="title"/>
        <ref name="shortdesc"/>
        <optional>
          <ref name="prolog"/>
        </optional>
        <optional>
          <ref name="body"/>
        </optional>
      </define>
    </include>
  </div>
</grammar>

When the DITA architect edits the document-type shell to integrate the element configuration module, they also need to do the following:

• Remove the include statement for topicMod.rng
• Add <section> to the "ID-DEFINING ELEMENT OVERRIDES" division