When placing an order, you can choose its validity period (time in force), which includes 「day」 and 「good till cancelled」.
Unfilled orders during the morning and afternoon sessions will be cancelled after the afternoon session ends;
Unfilled orders during the after-hours trading session will be cancelled after the after-hours trading session ends.
Unfilled orders during a trading day will be cancelled after the market closes.
2.1 Cash settlement contracts: An order remains valid until it is filled or cancelled, or the contract expires.
2.2 Physical delivery contracts: An order remains valid until two trading days before the last trading day or first notice day. Unfilled orders will be cancelled after the market closes.
2.3 Physical delivery US futures options contracts: An order remains valid until one trading days before the last trading day.
Note: In order to avoid the risk of physical delivery, you cannot submit a good till cancelled order after two trading days before the last trading day or first notice day. If necessary, you can select "day" when placing an order.