These are phrases used in placing orders to either buy or sell securities. If you are placing an order to purchase ten contracts of Dell October $40 calls at a limit of 4 5/8 for the day, you would tell your broker you were placing a day order for 10 contracts of Dell October $40 strike calls to buy at a limit of 4 5/8. This gives your broker all the information he or she needs to place the order.