(Cdn$ in millions) 2012 2011 Net operating loss carry forwards  $ 119 $ 24 Capital allowances in excess of depreciation  207 473 Decommissioning and restoration provisions  (46) 18 Amounts relating to non-coterminous partnership year-ends  (236) 80 Unrealized foreign exchange losses  (42) (25) Other temporary differences 96 131 $ 98 $ 701 d) The amount of deferred tax expense charged (credited) to the income statement is as follows: e) Temporary differences giving rise to deferred income and resource tax assets and liabilities are as follows: Generations 107 December 31, December 31, (Cdn$ in millions) 2012 2011 Net operating loss carry forwards  $ 569 $ 577 Property, plant and equipment  (112) (19) Decommissioning and restoration provisions  29 35 Amounts relating to non-coterminous partnership year-ends  (215) (278) Unrealized foreign exchange (23) (65) Other temporary differences (19) (70) Deferred income and resource tax assets $ 229 $ 180 Net operating loss carry forwards  $ (505) $ (615) Property, plant and equipment  5,934 5,830 Decommissioning and restoration provisions  (256) (204) Amounts relating to non-coterminous partnership year-ends  255 428 Other temporary differences 19 (97) Deferred income and resource tax liabilities  $ 5,447 $ 5,342