There are a certain number of strikes under the category “additional strikes which may be enabled intraday”
How does it work? Will those strikes available for whole month until expiry?
Refer this xls to understand better. http://www.nseindia.com/content/fo/sos_scheme.xls
If the Stock prices moves significantly during the day, the Exchange may choose to add additional contract of newer strike prices.
The Exchanges allow trading in a certain number of ITM,OTM contracts. On a given day let's assume the stock price moves by a big percentage, the Exchange will have to introduce newer strikes to maintain the balance.
Eg: Let's say ITS Spot price is 350 and there are 320,330,340,350,360,370,380 call options trading.
320,330,340 = ITM options
350 = ATM option
360,370,380 = OTM options
On a given day if ITC gains 12%, then SPOT = 392, then all the calls become ITM calls. In such cases, the Exchange introduces additional strikes.