History of the United States (1918–1945) (especially poor people) and prevent inflation. Tires were the first item to be rationed in January 1942 because supplies of natural rubber were interrupted. Gasoline rationing proved an even better way to allocate scarce rubber. By 1943 one needed government issued ration coupons to purchase typewriters, sugar, gasoline, bicycles, footwear, fuel oil, silk, nylon, coffee, stoves, shoes, meat, cheese, butter, margarine, canned foods, dried fruits, jam, and many other items. Some items—like new automobiles and appliances—were no longer made. The rationing system did not apply to used goods (like clothes or cars). The ration system was complex and confusing, but
Digital Item MPEG-21 proposes to facilitate a wide range of actions involving Digital Items so there is a need for a very precise description for defining exactly what constitutes such an item. A "Digital Item Declaration" (DID) is a document that specifies the makeup, structure and organisation of a Digital Item. The purpose of the Digital Item Declaration is to describe a set of abstract terms and concepts, to form a useful model for defining what a Digital Item is. Following this model, a Digital Item is the digital representation of an object, which is managed, described or exchanged within the model.