(a) The unitrust amount to be distributed by the express total return unitrust may be determined in the governing instrument by reference to the net fair market value of the trust's assets determined annually or averaged on a multiple year basis.
(b) The terms of the governing instrument of an express total return unitrust may provide that:
(1) Assets for which a fair market value cannot be readily ascertained shall be valued using valuation methods that the trustee considers reasonable and appropriate.
(2) Assets, such as a residence property or tangible personal property, used by the trust beneficiary entitled to the unitrust amount may be excluded from the net fair market value for computing the unitrust amount.