AE&P ratio.
(iv) AE&P ratio. Except as provided in this paragraph or paragraph (b)(3)(iv) of this section, the term AE&P ratio means the fraction of which the numerator is historical AE&P, and the denominator is the sum of historical AAA and historical AE&P. Notwithstanding the preceding sentence, if the AE&P of the ETSC is less than or equal to zero as of the beginning of a taxable year, then the AE&P ratio is zero for such year and all subsequent taxable years of the ETSC period.