Boundary that defines what is considered to be production in an accounting system. In the NIPAs, the boundary includes the production of most goods and services for the market, the production of goods or fixed assets by producers for their own final use as consumption or as fixed investment, and certain nonmarket activities, such as the provision of most goods and services by government agencies and by nonprofit institutions, and the production of housing services by owner-occupied housing. It excludes other nonmarket activities such as unpaid household work, volunteer work, and the natural growth of forests.