David Sherman, professor of accounting, was interviewed about expanding his 2009 FAS 157 Answer Book due to changing fair value rules. "...if there was something radical, it was the revision the FASB made in April, where they said you could take the change in value and separate the part that's due to credit risk from the part that's due to inactivity in the market - and the part that's due to the market you don't have to put through to income. Also, the fair-value hierarchy with Level 1, 2 and 3 assets and liabilities - this is really a remarkable development. It's accounting, but it also is a broad business issue now in terms of what the implications are. People say things like, "From now on we're only going to take Level 1 as collateral." Investors, lenders and security analysts are making business decisions using this new vocabulary," explains Sherman.