https://www.census.gov/eos/www/naics/faqs/faqs.html#q2 (NAICS / SIC code) Frequently asked questions http://www.census.gov/eos/www/naics/faqs/faqs.html North American Industry Classification System https://www.census.gov/eos/www/naics/faqs/faqs.html#q9 SIC was replaced https://www.census.gov/eos/www/naics/faqs/faqs.html#q5 U.S. Census Bureau FAQs NAICS Frequently Asked Questions- - US Census Bureau https://www.census.gov/eos/www/naics/faqs/faqs.html#q8 NAICS Get more information on NAICS. http://www.census.gov/eos/www/naics/faqs/faqs.html https://www.census.gov/eos/www/naics/faqs/faqs.html#q8 NAICS code there is a robust FAQ. United States Census Bureau Website http://www.census.gov/eos/www/naics/faqs/faqs.html NAICS FAQs North American Industry Classification System frequently asked questions Census website U.S. Census Bureau’s guidelines https://www.census.gov/eos/www/naics/faqs/faqs.html#q1 http://www.census.gov/eos/www/naics/faqs/faqs.html (NAICS) newer and more specific E