Ill. Admin. Code tit. 83 § 411.160
The reports required to be filed by this Part shall be submitted to the Commission and available to the public in both printed and electronic form. The printed version shall be the official version filed with the Commission's Chief Clerk. Computerized data and information filed as part of a report that is stored by a jurisdictional entity on a personal computer shall be provided in Microsoft Office, or other format agreed to by Commission Staff, and delivered to the Commission's offices via electronic mail or portable storage media as agreed to by the Commission Staff. Underlying data provided to the Commission shall be available to the public to the extent that it is not proprietary information. A jurisdictional entity shall report the required information on both a system-wide and operating areas basis. A jurisdictional entity shall submit the required information in a consistent format each year that facilitates comparisons across time periods and that uses non-technical language. A jurisdictional entity's reports shall be available to the public from the jurisdictional entity and from the Commission. A jurisdictional entity shall keep copies of its reports at its public offices.
Ill. Admin. Code tit. 83, § 411.160