Explanation:

- Depreciation: This refers to the reduction in the value of assets over time. It is considered in GDP to obtain Net National Product but is not part of the national income calculation itself.

- Net factor income from abroad: This includes earnings from foreign investments minus payments to foreign investors. It is added to GDP to calculate national income.

- Operating surplus: This is the profit earned from production processes, part of the income generated in an economy.

- Mixed income: It is the income earned by households from both labor and ownership of enterprises. It forms a part of national income.