The usefulness of the then-prevailing definition of extraordinary items came under review in 1973,and the APB concluded that similar items of revenues and expenses were not being classified in the same manner across the spectrum of business enterprises. The Board also concluded that businesses were not interpreting APB Opinion No.9 in a similar manner and that more specific criteria were needed to ensure a more uniform interpretation of its provisions. In APB Opinion No. 30, “Reporting the Results of Operations,” extraordinary items were defined as events and transactions that are distinguished by both their unusual nature and their infrequency of occurrence. These characteristics were originally defined as follows.