Property, plant and equipment are recognised at cost, less accumulated depreciation and any impairment losses.
Depreciation is calculated on a straight line basis over the estimated useful life and taking account of any residual value at the end of that period. Property, plant and equipment comprising parts that have different useful lives are treated as separate components. Gains or losses realised upon the disposal or retirement of an asset consist of the difference between the selling price and the carrying amount of the asset, less direct selling expenses. Gains or losses are recognised as other operating income or other operating expense.