accounts, or as allowed for taxation purposes, especially if there is price inflation. In principle, CFC is calculated using the actual or estimated prices and rentals of fixed assets prevailing at the time the production takes place, and not at the times fixed assets were originally acquired. The "historic costs" of fixed assets, i.e., the prices originally paid for them, may become quite irrelevant for the calculation of consumption of fixed capital, if prices change sufficiently over time. Unlike depreciation as calculated in business accounts, CFC in national accounts is, in principle, not a method of allocating the costs of past expenditures on fixed assets over subsequent accounting periods. Rather, fixed assets at a given moment in time are valued according to the remaining benefits derived from their use. Depreciation charges in business accounts are adjusted in national accounts from historic costs to current prices, in conjunction with estimates of the capital stock. In addition to gross measures of output and income such as GDP and gross national income (GNI), National Accounts include net measures such as net domestic product (NDP) and net national income (NNI), derived by deducting CFC from the corresponding gross measure. GDP is the most accurate measure of aggregate economic activity. However, NNI represents the income actually available to finance consumption and new investment (excluding the replacement of capital consumed in production). It is therefore a more accurate measure of economic welfare. Inclusions In UNSNA, included are: all tangible and intangible fixed assets owned by producers. fixed assets constructed to improve land, such as drainage systems, dykes, or breakwaters or on assets which are constructed on or through land - roads, railway tracks, tunnels, dams, etc. Losses of fixed assets due to normal accidental damage, i.e. damage caused to assets used in production resulting from their exposure to the risk of fires, storms, accidents due to human errors, etc. interest costs incurred in acquiring fixed assets, which may consist either of actual interest paid on borrowed funds, or the loss of interest incurred as a result of investing own funds in the purchase of the fixed asset, instead of a financial asset. Whether owned or rented, the full cost of using the fixed asset in production is thus measured by the actual or imputed rental on the asset, and not by depreciation alone. If the fixed asset is actually rented under an operating lease or similar