For Cover Order trades, the SL automatically taken by the software is at 5%. So the required margin blocked in Cover Order facility is 5%.
Example 1: If any stock like Ranbaxy futures requires a margin of 34% in NRML mode, the margin required in cover order would be fixed at 5% of the turnover of each lot. i.e if Ranbaxy futures trading at Rs 400 and has a market lot of 500, then the entire turnover of 1 lot Ranbaxy futures is Rs 200000. In NRML the required margin would be 34% i.e. Rs 68000/- whereas in cover order facility it would be 5% i.e. Rs 10000/-. Here it seems that there is an exposure of 6.8 times in cover order.
Example 2: Reliance futures requires margin of 11% in NRML mode. It would be 5% in cover order mode. If Reliance is trading at Rs 870/- with market lot of 250, then turnover of 1 lot Reliance future is Rs 2,17,500/-. In NRML the margin required is 11% i.e. Rs 23925/- but in cover order it would be at 5% i.e. 10,875/-. Here it apparently seems that there is 2.2 times exposure in cover order.
Example 3: Nifty futures trading at 6060 with market lot 50 and margin required 7% in NRML and 5% in Cover order. So, margin required would be 21,210/- in NRML and 15,150/- in CO.
Example 4: Banknifty trading at 10,360 with market lot of 25 and required margin of 12% in NRML and 5% in CO. So margin required would be 31,280/- in NRML and 12,950/-in CO.
In case of MIS trades, the margin required is just half the margin required in NRML mode. But the margin required in CO is as per above calculation. It has been identified that only in Nifty futures, it is better for the trader to execute positions in MIS mode rather than in CO mode as the margin required is less in MIS compared to CO. This is an exception and the NOW is working on the same. For all other scripts, CO is better than MIS in terms of margin requirement.
Please note in case of MIS only Span Margin is calculated and block for trading, but in case of CO (Cover Order) trade in future segment NOW Surveillance systems calculate SPAN+ Exposure Margin for execution.
Hope this helps.
For any further clarification, please feel free to get back.