Data and information should be based on historical or original cost methodology, to the extent possible. Data should be derived from publicly available reports filed with the Department of Telecommunications and Cable, the Department of Public Utilities, the Federal Communications Commission, the Federal Energy Regulatory Commission, such as the Federal Energy Regulatory Commission's Form No. 1, or other reports filed with state or regulatory agencies. The source of any data shall be identified. Calculations made in connection with these figures should be provided to the complainant upon request, as should the computation of any rate determined by using the formula adopted for calculating reasonable attachments rates in Massachusetts;
220 CMR, § 45.04