Table 1.

Occupational categories according to DISCO-88.

Occupational category	DISCO-88
Holtermann’s group (occupations that are strongly associated with heavy lifting)
	712. Building frame and related trades workers
	921. Agricultural, forestry and fishery laborers
	931. Construction laborers
	933. Transport and storage laborers
Other blue-collar workers (occupations in which heavy lifting is less likely to occur)
	All workers with a first digit DISCO-code equal to 6 (agricultural trades workers), 7 (craft and related trades workers), 8 (plant and machine operators and assemblers), or 9 (elementary occupations). Except those that belong to Holtermann’s group.