Its a Delta Award ticket in Business Class on Alitalia. Issued in D class (business class). I spoke with Alitalia offices in Europe, and they told me its basically a forward section of the cabin with "enhanced" beverage and snack service. It also provides access to Business Class lounges at FCO (on departure).
Lounge access is the main reason I redeemed that extra 5000 miles (vs 25000 miles for coach