In the following example, the complex type book represents a standard book and the complex type old-book is a restriction because a lexical pattern constraint (pattern value ="[0-9]{2}-[A-Z]{5}-[0-9]") has been added. The example includes a rule named processOldBook that matches "Hamlet" with the title of an OldBook object.

Here is the schema:

<complexType name= "book">
 <sequence>
   <element name="ident" type="string"/>
   <element name="title" type="string" />
 </sequence>
</complexType>
<complexType name="old-book">
 <complexContent>
  <restriction base="book">
    <sequence>
     <element name="ident">
      <simpleType>
        <restriction base="string">
          <pattern value="[0-9]{2}-[A-Z]{5}-[0-9]">
        </restriction>
      </simpleType>
     </element>
    </sequence>
  </restriction>
 </complexContent>
</complexType>

Here is the XOM representation:

class Book extends IlrXmlObject
{
   ...
     String ident;
     String title;
   ...
}
class OldBook extends Book
{
   ...
}

And here is the rule:

rule processOldBook
{
   when {
        OldBook ( title equals "Hamlet" );
   }
   then {
      ...
   }
}

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