<!-- db0.rng -->

<grammar xmlns="http://relaxng.org/ns/structure/1.0">

<define name="Title">

  <element name="title"><text/></element>

</define>

<define name="Text">

  <oneOrMore>

    <element name="para"><text/></element>

  </oneOrMore>

</define>

</grammar>

<!-- db1.rng -->

<?xml version="1.0" encoding="UTF-8"?>

<grammar xmlns="http://relaxng.org/ns/structure/1.0">

<start>

 <element name="book">

   <oneOrMore>

     <element name="part">

       <ref name="Title"/>

       <ref name="Text"></ref>

     </element>

   </oneOrMore>

 </element>

</start>

<include href="db0.rng"></include>

</grammar>

<!-- db2.rng -->

<?xml version="1.0" encoding="UTF-8"?>

<grammar xmlns="http://relaxng.org/ns/structure/1.0">

<start>

 <element name="book">

   <optional>

     <element name="info">

       <element name="title"><text/></element>

     </element>

   </optional>

  <zeroOrMore>

    <element name="part">

      <ref name="Title"/>

      <ref name="Text"></ref>

      <zeroOrMore>

        <element name="chapter">

          <ref name="Title"/>

          <ref name="Text"></ref>

        </element>

      </zeroOrMore>

    </element>

  </zeroOrMore>

</element>

</start>

<include href="db0.rng"></include>

</grammar>