(a) Such record shall be divided into continuing property record units which shall be arranged to conform with the operating property or the fixed capital accounts and shall include a description of each of such units.

(b) The original cost of each of such units shall be set forth provided that in those cases where the original cost cannot be ascertained without unreasonable expense, such original cost shall be estimated.

(c) Except as otherwise provided herein, there shall be shown for property hereafter installed, and for present property so far as can be ascertained, either in such record or in supporting data thereto, for each of such units, the date when charged to operating property or fixed capital, the location of the property, the manufacturer's name and any number or other identification mark imprinted thereon, the accounting company number or designation, and such other description as may be necessary to plainly identify the property and the associated original cost thereof.

(d) When meters or major units of power plant, pumping or purification equipment have been retired and subsequently reinstalled, the date when such property was first charged to operating property or fixed capital shall also be shown.

(e) Such property record shall show separately the units located in each city, village or town, and in the case of New York City in each borough, and in each power plant, pumping plant or purification plant. When a corporation desires a modification of this requirement, application should be made to the commission.

(f) There shall be shown by appropriate reference the source of all entries; and all drawings and computations and other detail records, supporting either the quantities or the cost included in the continuing property record, shall be retained.

(g) The original cost of each parcel of land and each structure owned in fee shall be set forth and no further subdivision need be shown.

(h) The original cost of easements for right of way shall be separately set forth for each transmission or distribution line.

(i) Property consisting of a large number of similar units may be grouped and only the average unit cost need be set forth for similar units of each size installed during a calendar year, except that in the case of Account 325, Meter Installations, separate unit costs for ordinary small inside meter installations need not be set forth for each year of installation.