sentences:  Buyback contracts in the oil sector, for instance, were arranged in which the contractor funded all the investments, and then received remuneration from the National Iranian Oil Company (NIOC) in the form of an allocated production share, then transferred operation of the field to NIOC after a set number of years, at which time the contract was completed.In February 2007 the government unveiled its new buyback-contract formula, which significantly extended the length of the contracts to as long as 20 years.The buy-back scheme is a formula used by the Iranian government to attract foreign investment.