Classes of supply

The United States Army divides supplies into ten classes of supply. The North Atlantic Treaty Organisation (NATO) uses only the first five, which NATO allies have agreed to supply to one another based on a NATO Standardization Agreement (STANAG). The other classes of supply remain in national hands.

(Source - NATO Logistics Handbook, November 2012)

Class VI is usually associated with liquor store on a U.S. military base, typically a U.S. Army or U.S. Air Force installation.