28 Tex. Admin. Code § 11.703
Each formula or method for calculating the schedule of charges must be accompanied by adequate detail including assumptions to justify that the charges produced by the formula or method are not excessive, inadequate, or unfairly discriminatory as defined in §11.706 of this title (relating to Factors To Be Considered in Determination of Reasonability of Rates).
Source Note:The provisions of this §11.703 adopted to be effective January 1, 1980, 4 TexReg 4626; amended to be effective August 17, 1992, 17 TexReg 5359.