Accounting for Interest Payment for GASB87 and SFFAS54

Under both the GASB87 and SFFAS54, it appears like 'Interest Expense' is the Interest Portion of a Payment. For example, if Payment Due Date is 01-Jan-23 for a Lease Starting on 01-Jan-23, when the 'Interest' is accounted for the first period, it is =0. The first payment being in advance, there is no interest portion embedded in it. Lets say Initial Liability is 100,000 and after deducting the first payment of 1000, remaining Liability balance of 99000, interest calculated on this say 99 from the first till next payment.

For the second month, lets say the payment amount is still 1000 and Interest of 99 is part of the second payment. Hence when second payment is accounted, 99 is Interest Expense and Principal Payment is 1000-99=901.