NRML is an abbreviation of Normal Orders, and it is mainly used for trading overnight in currency and equity futures and options. When the trader chooses NRML options, the trade doesn’t get auto squared off by the end of the day, unlike the order placed on Intraday. The margin requirements in NRML order are as per the overnight margins.
For instance, if a trader buys NIFTY futures and wishes to sell them after a few days, he can choose the NRML order option.