<xs:element name="person">
   <xs:complexType>
   <xs:sequence>
      <xs:element name="firstname" type="xs:string"/>
      <xs:element name="lastname" type="xs:string"/>
      
<xs:any minOccurs="0"/>
   </xs:sequence>
   </xs:complexType>
</xs:element>
<xs:element name="son" type="xs:string"/>
<xs:element name=”daughter” type="xs:string"/>

<person>
   <firstname>Danny</firstname>
   <lastname>Russell</lastname>
   
<son>Atlee</son>
</person>
<person>
   <firstname>Christine</firstname>
   <lastname>Slade</lastname>
   
<daughter>Susie</daughter>
</person>