When the amount of any unusual item includible in an income, operating revenue, or operating expense account for a single month is relatively so large that its inclusion in the accounts for that month would seriously distort those accounts, it may be included, upon order of the commission, in account 145, Miscellaneous Suspense, or account 272, Miscellaneous Unadjusted Credits, as appropriate, and distributed to such accounts and over such period as the commission, by order, may direct.