The difference between the quantity of natural gas received into a gas pipeline or distribution system (including gas received from storage) and the quantity of gas delivered to customers (including gas injected into storage) is called lost and unaccounted for gas. Lost and unaccounted for is commonly abbreviated as either LAUF or LUAF. There are a variety of reasons for lost and unaccounted for gas including leakage, theft, inaccurate meters, and the gas that is used to operate equipment on the system (which is unmetered). The cost of purchasing gas supply to cover lost and unaccounted for gas is part of the pipeline or distribution system’s cost of providing service.