Order validity is the period for which a placed order is valid.
Immediate-or-Cancel (IOC)
As the name suggests, an Immediate-or-Cancel (IOC) order is executed only if the entered quantity is fully matched; otherwise, it is cancelled. The entered quantity could be fully or partially available. If fully matched, the order is executed. If not fully matched, the entire order is cancelled. In the case of a partial match, the unmatched part is cancelled immediately. IOC orders are generally used when the user wants to fill as much quantity at the current market prices and avoid trades at different price points.
For example, if a user places an IOC order for a quantity of 100 and it is not filled immediately, the entire quantity of 100 will be cancelled. However, if a quantity of 40 is filled immediately, the remaining 60 will be cancelled. In the F&O segment, a partial match will happen in multiples of the stipulated lot size, while the remaining order will get cancelled.
Day Order
A Day Order, as the name suggests, remains valid until the end of the trading day. This order will be passive in the order book if not filled immediately and will continue to remain until the end of the trading day. A partial match is possible for day orders, and in case of a partial match, the remaining quantity will stay passive in the order book until filled or until the end of the trading day.
For example, if a user places a day order for a quantity of 100 and it is not filled immediately, the entire quantity of 100 will be in the order book. This quantity of 100 will be cancelled at the end of the trading day if not filled. If a quantity of 40 is filled immediately, the remaining 60 will remain passive in the order book until filled or until the end of the trading day.