the limit book when it is received is marketable. For example, if a stock is asked for $86.41 (large size), a buy order with a limit of $90 can be filled right away. Similarly, if a stock is bid $86.40, a sell order with a limit of $80 will be filled right away. A limit order may be partially filled from the book and the rest added to the book. Both buy and sell orders can be additionally constrained. Two of the most common additional constraints are fill or kill (FOK) and all or none (AON). FOK orders are either filled completely on the first attempt or canceled outright, while AON orders stipulate that the order must be filled with the entire number of shares specified, or not filled at all. If it is not filled, it is still held on the order book for later execution. Time in force A day order or good for day order (GFD) (the most common) is a market or limit order that is in force from the time the order is submitted to the end of the day's trading session. For stock markets, the closing time is defined by the exchange. For the foreign exchange market, this is until 5 p.m. EST/EDT for all currencies except the New Zealand Dollar. Good-til-cancelled (GTC) orders require a specific cancelling order, which can persist indefinitely (although brokers may set some limits, for example, 90 days). Immediate or cancel (IOC) orders are immediately executed or cancelled by the exchange. Unlike FOK orders, IOC orders allow for partial fills. Fill or kill (FOK) orders are usually limit orders that must be executed or cancelled immediately. Unlike IOC orders, FOK orders require the full quantity to be executed. Most markets have single-price auctions at the beginning ("open") and the end ("close") of regular trading. Some markets may also have before-lunch and after-lunch orders. An order may be specified on the close or on the open, then it is entered in an auction but has no effect otherwise. There is often some deadline, for example, orders must be in 20 minutes before the auction. They are single-price because all orders, if they transact at all, transact at the same price, the open price and the close price respectively. Combined with price instructions, this gives market on close (MOC), market on open (MOO), limit on close (LOC), and limit on open