<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" >
  <xs:element name="comments">
    <xs:complexType mixed="true">
      <xs:choice minOccurs="0" maxOccurs="unbounded">
        <xs:element name="para" type="xs:string"/>
        <xs:element name="heading" type="xs:string"/>
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="item">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="name" type="xs:string" />
        <xs:element name="comments" type="xs:string" minOccurs="0"/>
        <xs:element ref="comments" minOccurs="1" /> 
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>

