Nested structures

• All of these structures can nest straight-forwardly

<?xml version="1.0"?>
<element name="SONG" xmlns="http://relaxng.org/ns/structure/1.0">
  <element name="TITLE">
    <text/>
  </element>
  <oneOrMore>
    <element name="COMPOSER">
      <element name="NAME">
        <element name="GIVEN">
          <text/>
        </element>
        <element name="FAMILY">
          <text/>
        </element>
      </element>
    </element>
  </oneOrMore>
  <zeroOrMore>
    <element name="PRODUCER">
      <element name="NAME">
        <element name="GIVEN">
          <text/>
        </element>
        <element name="FAMILY">
          <text/>
        </element>
      </element>
    </element>
  </zeroOrMore>
  <optional>
    <element name="PUBLISHER">
      <text/>
    </element>
  </optional>
  <optional>
    <element name="LENGTH">
      <text/>
    </element>
  </optional>
  <optional>
    <element name="YEAR">
      <text/>
    </element>
  </optional>
  <oneOrMore>
    <element name="ARTIST">
      <text/>
    </element>
  </oneOrMore>
</element>