<!ELEMENT message (sender, receiver, subject?, date, body) >
<!ELEMENT body (para)+ >
<!ELEMENT sender #PCDATA >
<!ELEMENT receiver #PCDATA >
<!ELEMENT subject #PCDATA >
<!ELEMENT date #PCDATA >
<!ELEMENT para #PCDATA >
<! ATTLIST message lang (fr | en
| sp | it ) #REQUIRED >
