Standard Industrial Classification (SIC) system

The SIC system is used throughout the federal government to group establishments into industries. The SIC Division Structure makes it possible to collect and calculate establishment data by broad industrial divisions (labeled A through K), industrial groups (the 2-and 3-digit SIC levels), and specific industries (the 4-digit level). See the Standard Industrial Classification Manual, 1987 (Executive Office of the President, Office of Management and Budget), available in many libraries.