Example: Apply multiple constraints to a single document-type shell using RNG

Example

This section is non-normative.

Here is a list of the constraint modules and what they do:

File name	What it constrains	Details
example-TopicConstraint.mod	<topic>	Removes <abstract> Makes <shortdesc> required Removes <related-links> Disallows topic nesting
example-SectionConstraint.mod	<section>	Makes @id required
Not applicable	Highlighting domain	Reduces the highlighting domain elements to <b> and <i>
Not applicable	<ph>	Remove the <ph> element, allowing only domain extensions

The constraint modules that target the <topic> and <section > elements must be combined, since both elements are defined in topicMod.rng. The other constraints can be implemented directly in the document-type shell.

1. The DITA architect creates a constraint module that combines the constraints from example-TopicConstraint.mod and example-SectionConstraint.mod:

   <?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="topicMod.rng">
         <define name="section.attributes">
             <attribute name="id">
               <data type="NMTOKEN"/>
             </attribute>        
           <ref name="conref-atts"/>
           <ref name="select-atts"/>
           <ref name="localization-atts"/>
           <optional>
             <attribute name="outputclass"/>
           </optional>
         </define>
         <define name="topic.content">
           <ref name="title"/>
           <ref name="shortdesc"/>
           <optional>
             <ref name="prolog"/>
           </optional>
           <optional>
             <ref name="body"/>
           </optional>
         </define>
       </include>
     </div>
   </grammar>

2. In the document-type shell, they integrate the constraint module (and remove the inclusion statement for topicMod.rng):

   <div>
     <a:documentation>ELEMENT-TYPE CONFIGURATION INTEGRATION</a:documentation>
     <include href="acme-SectionTopicContraintMod.rng"/>
   </div>

3. To constrain the highlight domain, they modify the include statement for the domain module:

   <div>
     <a:documentation>MODULE INCLUSIONS</a:documentation>
     ...
     <include href="highlightDomain.rng">
       <define name="line-through.element">
         <notAllowed/>
       </define>
       <define name="overline.element">
         <notAllowed/>
       </define>
       <define name="sub.element">
         <notAllowed/>
       </define>
       <define name="sup.element">
         <notAllowed/>
       </define>
       <define name="tt.element">
         <notAllowed/>
       </define>
       <define name="u.element">
         <notAllowed/>
       </define>
     </include>
     ..  
   </div>

4. Finally, to disallow <ph>, they add the following statement to the constraint module:

         <define name="ph.element">
           <notAllowed/>
         </define>