this proportion is slightly above the average of of teachers in talis who said they regretted joining the profession oecd this isced classification defined tertiarytype a education as isced level a and tertiarytype b education as isced level b according to this classification tertiarytype a education programmes isced a are largely theorybased but are not exclusively offered at universities they aim to provide sufficient qualifications for entry to advanced research programmes and professions with high skill requirements these programmes have a minimal cumulative theoretical duration of three years although they typically last four or more years