Below are the sources through which Client can submit instruction for Block Mechanism.
accounts-with-nsdl
Process of Block Mechanism do away with the movement of shares from clients demat account for early pay-in and back to clients demat account if trade is not executed. In Block Mechanism securities remain blocked in clients demat account till BOD of pay-in, Corporate Action, if any, during this period, client remains registered holders in books of Company’s records.
Shares get block in the demat account of the client in favour of Clearing Corporation. If sale transaction doesn’t get executed, shares shall continue to remain in the client’s demat account and will be unblocked at the end of the T day.