Which of the following is NOT one of the primary government systems of occupational classification?

The International Labor Organization (ILO) is not one of the primary government systems of occupational classification. The ILO is a United Nations agency that deals with labor issues and promotes social justice and fair labor standards globally. While it does provide valuable resources and information about labor trends and employment statistics worldwide, it is not primarily a classification system for occupations.

On the other hand, ONET, the Dictionary of Occupational Titles (DOT), and the Occupational Outlook Handbook are all significant tools developed by the U.S. government for the purpose of occupational classification and labor market information. ONET provides a detailed database of occupational information in the United States, which includes job descriptions, required skills, and labor market trends. The DOT, although it is now largely superseded by O*NET, was historically a primary reference for occupational classification in the U.S., outlining various jobs and their requirements. Lastly, the Occupational Outlook Handbook offers insights into job outlooks, educational requirements, and work conditions for numerous professions, making it another key government source for understanding various occupations.

In summary, while the ILO is an important entity in the global realm of labor rights, it does not serve as a direct government classification system for occupations like the other three options listed.