NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS  NOTE 1 - STATEMENT OF SIGNIFICANT ACCOUNTING POLICIES continued  Loans and receivables are non-derivative financial assets with fixed or determinable payments that are not quoted  in an active market and are subsequently measured at amortised cost using the effective interest rate method.  Held-to-maturity investments are non-derivative financial assets that have fixed maturities and fixed or  determinable payments, and it is the Group’s intention to hold these investments to maturity. They are subsequently  measured at amortised cost using the effective interest rate method.  Available-for-sale financial assets are non-derivative financial assets that are either designated as such or that are  not classified in any of the other categories. They comprise investments in the equity of other entities where there  is neither a fixed maturity nor fixed determinable payments.  Non-derivative financial liabilities (excluding financial guarantees) are subsequently measured at amortised cost  using the effective interest rate method.  Financial assets are derecognised when the contractual right to receipt of cash flows expires or the asset is  transferred to another party whereby the entity no longer has any significant continuing involvement in the risks  and benefits associated with the asset. Financial liabilities are derecognised when the related obligations are either  discharged, cancelled or expire. The difference between the carrying value of the financial liability extinguished or  transferred to another party and the fair value of consideration paid, including the transfer of non-cash assets or  liabilities assumed, is recognised in profit or loss.  The carrying amounts of the Group’s assets are reviewed at each reporting date to determine whether there is any  indication of impairment. Where an indicator of impairment exists, a formal estimate of the recoverable amount is  made.  Exploration and evaluation assets are assessed for impairment in accordance with Note 1(b).  Development and production assets are assessed for impairment on a cash-generating unit basis. A cash-generating  unit is the smallest grouping of assets that generates independent cash inflows. Management has assessed its CGUs  as being an individual basin, which is the lowest level for which cash inflows are largely independent of those of  other assets. Impairment losses recognised in respect of cash-generating units are allocated to reduce the carrying  amount of the assets in the unit on a pro-rata basis.  An impairment loss is recognized in the income statement whenever the carrying amount of an asset or its cash- generating unit exceeds its recoverable amount.  - 64 -  f) Impairment of Non-Financial Assets  Derecognition  v) Financial liabilities  iv) Available-for-sale financial assets  iii) Held-to-maturity investments  ii) Loans and receivables 