If the contract at hand is an Indefinite Quantity type, then resulting Task or Delivery Orders each contain a unique period of performance or completion date (or some hybrid if established at the CLIN level), while the basic contract specifies the timeframe in which orders may be placed by the Government (See FAR 52.216-18 Ordering). For example, a basic contract might include a base year and two one-year option periods during which orders may be placed, and in the third year you might issue orders with a period of performance that extends a year or more beyond the basic contract ordering period (a function of requirement type and funding appropriation type).