Bids may be filed and searched by NAICS codes. Be sure that you are actually able to provide the product or service that you have included in your proposal.
Sometimes you will see the term SIC (Standard Industrial Classification), which refers to a code used from the 1930s to the 1990s, that also classified individual establishments according to their primary business activity.
Working jointly with Canada and Mexico, NACIS codes provide comparable statistics about the three countries. Detailed information, including NAICS Correspondence Tables, is available from the Bureau of the Census North American Industry Classification System (NAICS) page.