Interest on all indebtedness, temporary or permanent, is accrued quarterly, the computation of interest on temporary indebtedness being made as described in 1644-2.2, supra. The total amount of the quarterly accrual is initially charged to account 1420.1, Interest, for interest accrued during the development period and to account 4716, Interest on Indebtedness, for interest accrued during the operating period, the credit being to account 2132.1, Accrued Interest Payable—State of New York, for interest on advances made by the State, and to account 2132.2, Accrued Interest Payable—Temporary Loan Notes, for interest on funds borrowed from private investors. The cutoff point for interest initially charged to development costs is the date of substantial completion. The date of substantial completion, itself, is considered the first day of the operating period.