meal. K-ration: Individual ration. Designed as a short duration individual "assault" ration for paratroopers and other specialized light infantry forces. Declared obsolete in 1948. D-ration: Emergency ration. Bars of concentrated chocolate combined with other ingredients to provide high calorie content (intended as an emergency ration). A-rations were generally whatever meat and produce could be obtained locally, so there could be great variety from one theatre of operations to the next. B-rations were generally used when there was inadequate refrigeration for perishable A-rations. The composition of the D-ration did not change much throughout the war, but the C-ration developed many variations. A- and B-rations were only served at bases or established camps in rear areas as they require cooking. C-rations could be eaten hot or cold and required no special preparation or storage, so these could be served almost anywhere. During the war a new ration for assault troops, the K-ration, was developed. K-rations were originally intended to be used as short duration rations for only 2–3 days, but cost concerns and later standardization led to its overuse, contributing in some cases to vitamin deficiencies and malnourishment. There were various other special rations developed for specific circumstances, including: Type X Ration 5-in-1 ration 10-in-1 food parcel Mountain ration: , discontinued 1943 Jungle ration: , discontinued 1943 The Assault Lunch: Chocolate bars, caramels, dried fruit, chewing gum, peanuts, salt tablets, cigarettes, matches, and water purification tablets; total of , discontinued 1947 The Assault ration (Pacific Theater): 28 pieces of assorted hard candy, chewing gum, cigarettes and a chocolate peanut bar The Aircrew Lunch The AAF Combat Lunch Parachute Emergency Ration Liferaft Ration Airborne Lifeboat Ration Cold War rations Some of these specialized rations were discontinued during the war due to cost concerns, forcing commanders to adopt standardized rations in their place. The K- and D-rations were declared obsolete after World War II, but canned wet rations in the form of the C-ration (later the MCI) continued until 1983, when they were replaced by the Meal, Ready-to-Eat (MRE). Created during this era was the T-ration (or "T-rat"), a semi-perishable meal packaged, heated, and served in a tray pack similar to frozen meals. Present-day issuance Currently, the following rations are available to troops: Unitized Group Ration: standard group ration for field kitchens and garrisons, succeeding the A-, B-, and T-rations UGR-H&S (Heat & Serve): precooked, shelf-stable meals designed to be heated and served in