An overnight window through which banks can borrow emergency funds from the Reserve Bank of India at a penal rate above the repo rate, by dipping into their statutory liquidity reserves.
The corridor structure (MSF as ceiling, SDF as floor, repo in the middle) and the "above repo" relationship are standard money-market facts.
MSF (banks borrow from the RBI overnight, penal rate) versus the lender of last resort role; MSF is a routine standing facility, not a bailout. The MSF rate is above the repo rate, not below.
Overnight emergency borrowing from the RBI at a rate just above the repo rate; ceiling of the LAF corridor.