Here's a quote from Daniel Bell, from about 1980, talking about class structures in a post-industrial society.
If Education becomes decisive for class position, we will see developing the United States, and perhaps in other countries, a 4-tiered class system. What this 4-tiered system would come to is this:
1. A class of professional and technical and managerial employees in economic enterprises, in government, in research organizations, in social complexes (such as hospitals and the social welfare fields) and in the universities and cultural organizations.
2. A class of semi-skilled white-collar employees who would perform clerical tasks, sales tasks, and service operations for airlines, in recreational industries, real estate, banks and the like.
3. A class of skilled workers – technicians in factories, repair and maintenance workers, mechanics and the like.
4. A class of largely semi-skilled and unskilled workers for whom increasingly there would be little place in the society. http://www.urban75.net/forums/#_edn1
http://www.urban75.net/forums/#_ednref1 Daniel Bell, Sociological Journeys, Liberalism in the Post-Industrial Society, 1980, Pg.230-242