IOC stands for Immediate or Cancelled, and it is used for the order that needs to be executed immediately or stands canceled. IOC is generally used to buy large volumes of stocks.
IOC allows the trader to buy the stocks as soon as it displayed in the market; if the trader fails to buy, the system will remove the order. In case if there is a partial match of the IOC executed orders, the remaining unmatched order will be auto-canceled. Zerodha displays error 16388 in case of the order doesn’t match.