ASM is an additional margin levied by Clearing Corporations (NSCCL/ICCL) as part of enhanced risk management and surveillance measures to safeguard against extreme market volatility.
Margin shortfall occurs when you hold onto positions in your trading account without having a sufficient margin. It's different from the actual account balance. Penalties are levied on margin shortfall
Yes. Based on the margin availability, client can avail exposure in different segments at different time. However, maximum exposure given across segments are not exceeding the margins available.
ASM applicability depends on regulatory framework and market conditions. It may be modified or withdrawn as per instructions from Exchanges/Clearing Corporations.