(a) The commission shall adopt rules governing imputation of the price of a service.(b) Imputation is a regulatory policy the commission shall apply to prevent an incumbent local exchange company from selling a service or function to another telecommunications utility at a price that is higher than the rate the incumbent local exchange company implicitly includes in services it provides to the company's retail customers.(c) The commission may require imputation only of the price of a service that is: (1) not generally available from a source other than the incumbent local exchange company; and(2) necessary for the competitor to provide a competing service.(d) The commission may require imputation only on a service-by-service basis and may not require imputation on a rate-element-by-element basis.(e) For a service for which the commission may require imputation under Subsection (c) and that is provided under a customer specific contract, the commission: (1) may require imputation only on a service-by-service basis within the contract; and(2) may not require imputation on a rate-element-by-element basis. Acts 1997, 75th Leg., ch. 166, Sec. 1, eff. Sept. 1, 1997.