laws of June 7 and December 7, 2010 Operating profit before depreciation and amortization Net changes in fair value on Energy and Commodity derivatives... Group accounting standards 1 1 D' eclaration of conformity and Group accounting policies 1 2 Changes in accounting methods at January 1, 2011 1 3 S' ummary of the principal accounting and valuation methods 17 17 17 17 Note 16.