Imagine that you place an order to purchase 100 stocks. 50 stocks are bought in NSE, 50 in NSE, and 50 in BSE. You can then sell the stocks using the SOR condition. 50 stocks must be sold that are BSE, 50 NSE. If you sell using SOR there is a possibility that shares may come in a different combination.let's take an example, 75 in BSE and 25 in NSE. This means that you would end up short selling 25 shares of NSE and 25 shares of NSE.