Brokerage firms have a limit on the maximum open interest across all their clients' F&O positions. When this limit (PDF) is about to be exceeded, Zerodha may block new NRML orders for the respective currency pairs.
Exchange rules state that a client's total gross open positions for a currency pair should not exceed the specified limits.
While MIS orders can still be placed, they cannot be converted to NRML for contracts where new NRML orders are blocked. However, there are no restrictions on the day of currency expiry.
Client-level gross open positions are computed as follows:
- Long Futures, Long Calls, and Short Puts are considered Long positions.
- Short Futures, Short Calls, and Long Puts are considered Short positions.