business to another business after use, locally or overseas. So, the same asset can be counted twice or more. In principle, expenditure on used assets is excluded from capital formation, but in practice it is often included. Another reason has to do with the complexities of trade, in particular trade in services and international trade. Not only can it be difficult to correctly identify, survey and allocate particular financial incomes and expenditures, but also revaluations of assets occur, creating problems of how to value goods and services as such. At the highest level, due to the expansion of foreign trade, a fraction of local value-added may consist of the local inflation of foreign-produced value-added, simply because imported foreign products are resold locally, at inflated prices, without any corresponding additional local production occurring. This may not necessarily create problems of double counting locally, but if we want to estimate world GDP, we may face double counting problems of some kind. References See also National accounts United Nations System of National Accounts (UNSNA) value added GDP Real prices and ideal prices Intermediate consumption Management accounting National accounts