NAICS is an industry classification system developed by the statistical agencies of Canada, Mexico, and the United States. Created against the background of the North American Free Trade Agreement (NAFTA), it is designed to provide common definitions of the industrial structure of the three countries and a common statistical framework to facilitate the analysis of the three economies.\
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The structure of NAICS is hierarchical. The numbering system that has been adopted is a five-part, six-digit numeric code, of which the first five digits are used to describe the NAICS levels that will be used by the three countries to produce comparable data.\
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The first two digits designate the sector, the third digit designates the subsector, the fourth digit designates the industry group, and the fifth digit designates the industry. The sixth digit is used to designate national industries. A zero as the sixth digit indicates that there is no further national detail.