(2) A fiduciary shall allocate to income, without provision for amortization of premium, an amount received as interest on an obligation to pay money to the fiduciary, including an amount received as consideration for prepaying principal.
(3) A fiduciary shall allocate to principal an amount received from the sale, redemption, or other disposition of an obligation to pay money to the fiduciary.
(4) A fiduciary shall allocate to income the increment in value of a bond or other obligation for the payment of money bearing no stated interest but payable or redeemable, at maturity or another future time, in an amount that exceeds the amount in consideration of which it was issued. If the increment in value accrues and becomes payable pursuant to a fixed schedule of appreciation, it may be distributed to the beneficiary who was the income beneficiary at the time of increment from the first principal cash available or, if none is available, when the increment is realized by sale, redemption, or other disposition. If unrealized increment is distributed as income but out of principal, the principal must be reimbursed for the increment when realized. If, in the reasonable judgment of the fiduciary, exercised in good faith, the ultimate payment of the bond principal is in doubt, the fiduciary may withhold the payment of incremental interest to the income beneficiary.