<!ELEMENT order-list (order+)>
<!ELEMENT order (cliente, linea-ordine+)> 
<!ELEMENT customer (name, address, shipment-address?)> 
<!ELEMENT name (#PCDATA)>
<!ELEMENT address (#PCDATA)>
<!ELEMENT shipment-address(#PCDATA)>
<!ELEMENT order-line EMPTY>

<!ATTLIST order
    status (open|closed) #REQUIRED
    date CDATA #IMPLIED>
<!ATTLIST customer
    category CDATA #IMPLIED>
<!ATTLIST order-line
    product CDATA #REQUIRED
    qty CDATA 1
    price CDATA #REQUIRED>