(a) Each utility shall so keep its books of account, and all other books, records, and memoranda which support in any way the entries in such books of account, as to be able to furnish readily full information as to any item included in any account. Each entry shall be supported by such detailed information as will permit a ready identification, analysis, and verification of all the facts relevant thereto.

(b) The books and records referred to herein include not only accounting records in a limited technical sense, but all other records such as minute books, stock books, reports, correspondence, memoranda, engineering records, calculations, drawings, etc., which may be useful in developing the history of or facts regarding any transaction.

(c) Except as authorized by this commission, all operating, accounting or financial papers, records, books, invoices, stubs, maps, or documents or any papers or records which support entries to any of the accounts or which are necessary for an analysis shall be retained permanently. All such records shall be accessible, at all times, to the authorized representatives of the commission at a location within the State of New York.

(d) Subdivisions of any account in the system of accounts prescribed herein and clearing, temporary, or experimental accounts may be kept, provided that such subdivisions or additional accounts do not impair the integrity of the prescribed accounts. The titles of all subdivisions or subaccounts shall refer by number and title to the account or accounts of which they are subdivisions.

(e) All charges to the accounts prescribed in this system for electric plant, income, operating revenues and operating expenses shall be just and reasonable and any payments by the utility in excess of just and reasonable charges shall be included in account 1538, Miscellaneous Income Deductions.

(f) The numbers prefixed to account titles are to be considered as part of the titles. Each utility may, however, adopt a different system of account numbers provided that the numbers herein prescribed shall appear in the descriptive headings of the ledger accounts. When the same account number is used in systems of accounts prescribed for different classes of operations conducted by one utility, the initial letters E, G, O, R, S, and W may be prefixed to identify the account with electric, gas, omnibus, rail line, steam heating, or water, respectively. Accounts for common utility plant and operations shall be designated by the word “Common.”