has been proposed as an alternative to an implied zero valuation of environmental assets and as a way of measuring the sustainability of welfare levels in the presence of environmental degradation. Macroeconomic data not derived from the national accounts are also of wide interest, for example some cost-of-living indexes, the unemployment rate, and the labor force participation rate. In some cases, a national-accounts counterpart of these may be estimated, such as a price index computed from the personal consumption expenditures and the GDP gap (the difference between observed GDP and potential GDP). Main elements The presentation of national accounts data may vary by country (commonly, aggregate measures are given greatest prominence), however the main national accounts include the following accounts for the economy as a whole and its main economic actors. Current accounts: production accounts which record the value of domestic output and the goods and services used up in producing that output. The balancing item of the accounts is value added, which is equal to GDP when expressed for the whole economy at market prices and in gross terms; income accounts, which show primary and secondary income flows - both the income generated in production (e.g. wages and salaries) and distributive income flows (predominantly the redistributive effects of government taxes and social benefit payments). The balancing item of the accounts is disposable income ("National Income" when measured for the whole economy); expenditure accounts, which show how disposable income is either consumed or saved. The balancing item of these accounts is saving. Capital accounts, which record the net accumulation, as the result of transactions, of non-financial assets; and the financing, by way of saving and capital transfers, of the accumulation. Net lending/borrowing is the balancing item for these accounts Financial accounts, which show the net acquisition of financial assets and the net incurrence of liabilities. The balance on these accounts is the net change in financial position. Balance sheets, which record the stock of assets, both financial and non-financial, and liabilities at a particular point in time. Net worth is the balance from the balance sheets (United Nations, 1993). The accounts may be measured as gross or net of consumption of fixed capital (a concept in national accounts similar to depreciation in business accounts). Notably absent from these components, however, is unpaid work, because its value is not included in any of the aforementioned categories of accounts, just as it