On June 30, 2001, the rules governing the accounting treatment for mergers and acquisitions changed dramatically. On that date, FAS 141 (Business Combinations) and FAS 142 (Goodwill and Other Intangible Assets) became effective, superseding APB No. 16 (Business Combinations) and APB 17 (Intangible Assets) which had been issued in 1971. Under the new rules, pooling of interests accounting is no longer acceptable under any circumstances; the purchase method of accounting for business combinations is now mandatory in order to be in compliance with GAAP. This method of accounting involves allocating the purchase price paid to the assets acquired (tangible and intangible) and liabilities assumed by major balance sheet caption. In this process, intangible assets must be recognized apart from goodwill if they meet one of two criteria: the contractual-legal criterion or the separability criterion. These intangible assets are then amortized over their remaining useful lives.