ISCO (International Standard Classification of Occupations) is a tool for organizing jobs (occupations) into a clearly defined set of groups according to the tasks and duties undertaken in the job.
The current taxonomy (ISCO-08) is a four-plus-two level hierarchically structured classification that allows all jobs in the world (currently XXXX) to be classified into 436 unit groups.
The main aims of ISCO are to provide:
- a basis for the international reporting, comparison and exchange of statistical and administrative data about occupations;
- a model for the development of national and regional classifications of occupations; and
- a system that can be used directly in countries that have not developed their own national classifications.
Within the Open Risk Manual the ISCO taxonomy is used to map occupations into an Occupational Risk Taxonomy
The ISCO groups form the most detailed level of the classification structure and are aggregated based on their similarity in terms of the skill level and skill specialization required for the jobs into:
- 10 Major groups
- 43 SubMajor groups
- 130 Minor groups
- 436 Unit groups
- 1701 Occupation descriptions
- 1241 Specialization descriptions (2942 Total Descriptions)
The classification is encoded in a numeric designation of the form CNNNN.N.N, where N are digits 0-9. The digit(s) after the first dot signify a concrete description of an occupation, an optional second dot signifies a specialization
As an example of a full occupational hierarchy:
- C1 - Major Group: Managers
- C12 - SubMajor Group: Administrative And Commercial Managers
- C121 - Minor Group: Business Services And Administration Managers
- C1211 - Unity Group: Finance Managers
- C1211.1 - Occupation: Financial Manager
- C1211.1.2 - Specialization: Bank Treasurer
Top Level ISCO Sections (Major Groups)
The Major Groups is the ISCO-8 highest level segmentation 
- ILO Website
- ISCO-08 was adopted through a resolution of a Tripartite Meeting of Experts on Labour Statistics held in December 2007. This resolution was subsequently endorsed by the Governing Body of the ILO in March 2008.