A.7.1. Example

<grammar
  datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes"
  xmlns="http://relaxng.org/ns/structure/1.0">
  <start>
    <ref name="library"/>
  </start>
  <define name="library">
    <element name="library">
      <oneOrMore>
        <ref name="book"/>
      </oneOrMore>
      <zeroOrMore>
        <ref name="author"/>
      </zeroOrMore>
      <zeroOrMore>
        <ref name="character"/>
      </zeroOrMore>
    </element>
  </define>
  <define name="author">
    <element name="author">
      <attribute name="id">
        <data type="ID"/>
      </attribute>
      <element name="name">
        <text/>
      </element>
      <element name="nickName">
        <text/>
      </element>
      <element name="born">
        <text/>
      </element>
      <element name="dead">
        <text/>
      </element>
    </element>
  </define>
  <define name="book">
    <element name="book">
      <ref name="id-attribute"/>
      <ref name="isbn"/>
      <ref name="title"/>
      <zeroOrMore>
        <element name="author-ref">
          <attribute name="id">
            <data type="IDREF"/>
          </attribute>
          <empty/>
        </element>
      </zeroOrMore>
      <zeroOrMore>
        <element name="character-ref">
          <attribute name="id">
            <data type="IDREF"/>
          </attribute>
          <empty/>
        </element>
      </zeroOrMore>
    </element>
  </define>
  <define name="id-attribute">
    <attribute name="id">
      <data type="ID"/>
    </attribute>
  </define>
  <define name="character">
    <element name="character">
      <ref name="id-attribute"/>
      <ref name="name"/>
      <ref name="since"/>
      <ref name="qualification"/>
    </element>
  </define>
  <define name="isbn">
    <element name="isbn">
      <text/>
    </element>
  </define>
  <define name="name">
    <element name="name">
      <text/>
    </element>
  </define>
  <define name="nickName">
    <element name="nickName">
      <text/>
    </element>
  </define>
  <define name="qualification">
    <element name="qualification">
      <text/>
    </element>
  </define>
  <define name="since">
    <element name="since">
      <data type="date"/>
    </element>
  </define>
  <define name="title">
    <element name="title">
      <text/>
    </element>
  </define>
</grammar>