The Settlement for Equity Delivery (payin of shares to the exchange) takes place on T+2 basis. It means the shares bought on “T” or Trading day (e.g. Monday) are to be received by the Buyer on T+2 day (i.e. Wednesday).
Similarly the shares sold on “T” (e.g. Monday) are to be delivered to the exchange by the seller on T+2 (Wednesday) to get the proceeds (cash) from the sale.
The failure of the seller to deliver the shares to the buyer on T+2 as obligated is called Short Delivery.