Tucked away at the bottom of its 2005 income statement issued last week, Ford Motor Company delivered a $251 million answer to a new accounting question—one that experts say is catching many companies unaware or just starting to get their attention.

Ford booked a $251 million charge to earnings to comply with Interpretation No. 47, a 34-page bundle of guidance issued by the Financial Accounting Standards Board last year to clarify how it expects companies to obey Statement No. 143—Accounting for Asset Retirement Obligations.