Part of gas sales agreement (GSA) clause between gas supplier and gas consumer. For instance, if a gas Seller fails to deliver a proper nomination of Buyer, then the quantity not supplied which exceeds a (2%-5% – depending on how the sides manage their negotiations) daily operational tolerance will be considered shortfall gas and Sellers will supply an equal quantity of such shortfall gas in the following month at the shortfall price. The shortfall gas price should be at a discounted price (50%-90% discount rate depends on how the sides manage their negotiations) of the Contract Price.