Section 4(7)(a) in The Delhi Electricity Regulatory Commission (Terms and Conditions for Determination of Wheeling Tariff and Retail Supply Tariff) Regulations, 2011
(a)AT&C Loss, which shall be measured as the difference between the net units input into the distribution system for sale to all its consumer and the units realised wherein the units realised shall be equal to the product of units billed and collection efficiency: