The System of National Accounts (SNA) prescribes that GDP statistics should include net income from merchanting (the difference between the sale price of merchanting products and the purchase price). This regulation is intended to reflect the fact that planning, deployment, financial, management, marketing, patent, and other technical services provided by enterprises engaging in merchanting unquestionably constitute domestic output. The widespread belief that GDP calculation should not include merchanting is based on a misunderstanding of the scope of GDP (all revenue derived from the sale of products via merchanting must be included in GDP). Net income from merchanting has constituted only 3.5%-4.4% of GDP in recent years.