Section 55.003 - Rule or Standard(a) A public utility may not impose a rule except as provided by this title.(b) A public utility may file with the commission a standard, classification, rule, or practice the utility follows.(c) The standard, classification, rule, or practice continues in force until: (1) amended by the utility; or(2) changed by the commission as provided by this subtitle. Acts 1997, 75th Leg., ch. 166, Sec. 1, eff. Sept. 1, 1997.