The following classification resulted from the 2020 OECD Survey on Public Service Leadership and Capability, which also used the same definitions as in the 2020 OECD Survey on the Composition of the Workforce in Central/Federal Governments. This classification defines the four main hierarchical levels of occupations.
The classification and the definition of the occupations are an adaptation of the International Standard Classification of Occupations (ISCO 08) developed by the International Labour Organization (ILO). Full definitions are available at www.ilo.org/public/english/bureau/stat/isco/isco08/index.htm.
The reason for the adaptation is that not all countries follow the ISCO model to classify their occupations in government, as the occupations included at the national level may differ due to specific legal and administrative frameworks.