the second is non-routine manual
the third is routine
"In the last 30 years the US labor market has been characterized by job polarization and jobless recoveries. In this paper we demonstrate how these are related. We first show that the loss of middle-skill, routine jobs is concentrated in economic downturns. In this sense, the job polarization trend is a business cycle phenomenon. Second, we show that job polarization accounts for jobless recoveries. This argument is based on the fact that almost all of the contraction in aggregate employment during recessions can be attributed to job losses in middle-skill, routine occupations (that account for a large fraction of total employment), and that jobless recoveries are observed only in these disappearing routine jobs since job polarization began. We then propose a simple search-and-matching model of the labor market with occupational choice to rationalize these facts. We show how a trend in routine-biased technological change can lead to job polarization that is concentrated in downturns, and recoveries from these recessions that are jobless".
