This excerpt taken from the PBR 6-K filed Jun 8, 2009.
Page: 120
5.
As mentioned in Note 1, due to the changes in accounting practices adopted in Brazil during 2008, the statements of income, cash flows and added value for the quarter ended March 31, 2008, as well as the supplementary information of segment reporting, which is not required by the accounting practices adopted in Brazil and is being presented to facilitate additional analysis, presented for comparison purposes, were adjusted and are being restated as established in NPC 12 - Accounting Practices, Changes in Accounting Estimates and Correction of Errors, approved by CVM Resolution 506/06.