N.Y. Comp. Codes R. & Regs. tit. 16, § 561.3 – Numbering system.

(a) The account numbering scheme used herein consists of a system of three-digit whole numbers as follows:
(100-199) Assets and Other Debits.
(200-299) Liabilities and Other Credits.
(300-399) Plant Accounts.
(400-432, 434-435) Income Accounts.
(433, 436-439) Retained Earnings Accounts.
(460-479) Revenue Accounts.
(600-699) Production, Transmission and Distribution Expenses.
(900-949) Customer Accounts, Sales and General Administrative Expenses.
(b) In certain instances, numbers have been skipped in order to allow for possible later expansion or to permit better coordination with the numbering system for other utility departments.
(c) The numbers prefixed to account titles are to be considered as part of the titles. Each utility, however, may adopt for its own purposes a different system of account numbers (see also general instruction 561.2, subd. [d]) provided that the numbers herein prescribed shall appear in the descriptive headings of the ledger accounts and in the various sources of original entry; however, if a utilty used a different group of account numbers and it is not practicable to show the prescribed account numbers in the various sources of original entry, such reference to the prescribed account numbers may be omitted from the various sources of original entry. Moreover, each utility using different account numbers for its own purposes shall keep readily available a list of such account numbers which it uses and a reconciliation of such account numbers with the account numbers provided herein. It is intended that the utility's records shall be so kept to permit ready analysis by prescribed accounts (by direct reference to sources of original entry to the extent practicable) and to permit preparation of financial and operating statements directly from such records at the end of each accounting period according to the prescribed accounts.