Consolidated  Notes to the  Financial  Statements Note 1 – Summary of significant accounting policies  (continued) Impairment of financial assets Derecognition of financial assets (o) Non-current assets and disposal groups held for sale (r) Property, plant and equipment Producing assets (q) Oil and gas assets Assets in development (p) Exploration and evaluation assets Exploration and evaluation expenditure incurred is accumulated  in respect of each identifiable area of interest. An area of interest  refers to an individual geological area where the presence of oil or  a gas field is considered favourable or has been proved to exist,  and in most cases will comprise an individual oil or gas field. Exploration and evaluation expenditure is recognised as an  exploration and evaluation asset in the year in which it is incurred,  provided the rights to tenure of the area of interest are current  and either:  Exploration and evaluation assets are initially measured at cost and  include acquisition of rights to explore, studies, exploratory drilling,  trenching and sampling and associated activities. General and  administrative costs are only included in the measurement of  exploration and evaluation costs where they are related directly  to operational activities in a particular area of interest. The carrying amounts of the consolidated entity’s exploration and  evaluation assets are reviewed at the end of each reporting period,  in conjunction with the impairment review process referred to in  Note 1(u), to determine whether there is any indication that the  assets have suffered an impairment loss. When an oil or gas field has been approved for development, the  accumulated exploration and evaluation expenditure is transferred  to oil and gas assets. The costs of oil and gas assets in development are separately  accounted for and include past exploration and evaluation costs,  development drilling and other subsurface expenditure, surface  plant and equipment and any associated land and buildings. When  commercial operation commences, the accumulated costs are  transferred to oil and gas assets – producing assets. The costs of oil and gas assets in production are separately  accounted for and include past exploration and evaluation costs,  past development costs and the ongoing costs of continuing to  develop reserves for production and to expand or replace plant  and equipment and any associated land and buildings. When production commences, the accumulated costs for the  relevant area of interest are amortised over the life of the area  according to the rate of depletion of the economically  recoverable reserves. Property, plant and equipment is stated at cost less accumulated  depreciation and accumulated impairment losses. Cost includes expenditure that is directly attributable to the  acquisition or construction of the asset. Finance costs related to the  acquisition or construction of qualifying assets are capitalised. Cost  may also include transfers from other comprehensive income of  any gain or loss on qualifying cash flow hedges of foreign currency  purchases of property, plant and equipment. Non-current assets and the assets of a disposal group classified as  held for sale are presented separately from the other assets on the  face of the statement of financial position. The liabilities of a  disposal group classified as held for sale are presented separately  from other liabilities on the face of the statement of  financial position. Non-current assets (including those that are part of a disposal  group) are not depreciated or amortised while they are classified as  held for sale. Non-current assets and disposal groups classified as  held for sale are measured at the lower of their previous carrying  amount and fair value less costs to sell.  Non-current assets and disposal groups are classified as held for  sale if their carrying amount will be recovered principally through a  sale transaction rather than through continuing use. This condition  is regarded as met only when the sale is highly probable and the  non-current asset or disposal group is available for immediate sale  in its present condition. Management must be committed to the  sale, which should be expected to qualify for recognition as a  completed sale within one year from the date of classification. Financial assets are derecognised when the rights to receive cash  flows from the financial assets have expired or when the  consolidated entity transfers substantially all the risks and rewards  of the financial assets. If the consolidated entity neither retains nor  transfers substantially all of the risks and rewards of ownership, it  derecognises the asset if it has transferred control of the assets. In respect of available-for-sale equity instruments, impairment  losses previously recognised in profit or loss are not reversed  through profit or loss. Any increase in fair value subsequent to  an impairment loss is recognised in other comprehensive income. With the exception of available-for-sale equity instruments, if, in  a subsequent period, the amount of the impairment loss decreases  and the decrease can be related objectively to an event occurring  after the impairment was recognised, the previously recognised  impairment loss is reversed through profit or loss. Financial assets, other than those at fair value through profit or loss,  are assessed for indicators of impairment at the end of each  reporting period. Financial assets are considered to be impaired  where there is objective evidence that, as a result of one or more  events that occurred after the initial recognition of the financial  asset, the estimated future cash flows of the asset have  been affected. For financial assets measured at amortised cost, the amount of  the impairment loss recognised in profit or loss is the difference  between the asset’s carrying amount and the present value of  estimated future cash flows, discounted at the financial asset’s  original effective interest rate. Impairment of trade receivables is  recognised in accordance with the accounting policy set out in  Note 1(l). When an available-for-sale financial asset is considered to  be impaired, cumulative gains or losses previously recognised in  other comprehensive income are reclassified to profit or loss. > exploration and evaluation expenditure is expected to be  recovered through successful development and exploration  of the area of interest, or alternatively, by its sale; or > exploration and evaluation activities in the area of interest have  not, at the end of the reporting period, reached a stage which  permits reasonable assessment of the existence of economically  recoverable reserves and active and significant operations in,  or in relation to, the area of interest are continuing. 72