structural:expansion, information:filtering, quality:corruption, stylistic:tone, information:classification
Government

The United Nations developed the International Standard Industrial Classification, which is a list of economic and social classifications. There is no distinct classification for an energy industry, because the classification system is based on activities, products, and expenditures according to purpose.

Countries in North America use the North American Industry Classification System (NAICS). The NAICS sectors #21 and #22 (mining and utilities) might roughly define the energy industry in North America. This classification is used by the U.S. Securities and Exchange Commission.