The categories are:
(i) Children (below 15 years), who are economically unproductive and need to be provided with food, clothing, education and healthcare.
(ii) Working age (15 to 59 years), who are economically productive and biologically reproductive. They comprise the working population.
(iii) The aged or elderly (60 years and above), who can be economically productive though they may have retired. They may be working voluntarily but they are not available for employment through recruitment.