Some more useful information which you won't see on their website,
Derivative products on NSE have two types of Settlement methods - Cash settlement for index derivatives and Physical settlement for stock derivatives.
In case you are holding derivative positions which are Physically settled on expiry, the outcomes of such contracts would be long or short position delivery in case the existing derivative position is not closed on expiry day before 15:30 IST.
If you hold Long futures, Long ITM Call and Short ITM Put option position then long stock will be assigned.
Due to physical delivery, in case there is a long position assigned, you would need to have the required margins to hold the long position which has been assigned.
In case your account does not have sufficient available funds, there will be liquidations in the account to get the account back to be margin compliant.
If you hold Short futures, Short ITM Call, Long ITM Put option position then short stock will be assigned.
Due to the physical delivery, in case there is a short position assigned and in the event you do not hold sufficient long quantity in your account, the short position goes to Auction. Buying the stock on the next day will not offset the short position which has been assigned due to the physical delivery. Once the position has been settled through the Auction the short position will be closed.
You can look for Archived circular section on NSE's website for past few years for information related to Physical delivery.
Then immediately next question rises, if I hold stock derivatives position till expiry,
(1) when long - from how many days prior to the expiry the additional margin obligation applies before liquidation starts and at what margin rate (if any)?
Ans) The margin requirement for the expiring derivatives position will start increasing by 20 % everyday starting from T-4 day.
(2) when short - from how many days prior to the expiry do I need to procure the required stock holdings?
Ans) On expiry day, you need to have long stock position in your account to offset the short stock assignment.