The following modalities are distinguished, which can be grouped:

• Illiteracy: individuals who cannot read or write.
• No studies: individuals who can read and write, but have not completed any type of studies.
• Primary studies: Certificate of Schooling, Primary Education or School leaving certificate.
• Vocational studies: Vocational training qualifications.
• Secondary Studies: Lower Secondary Education and equivalent studies, Certificate of Compulsory Secondary Education (ESO), Upper Secondary Education or BUP, LOGSE or LOE Baccalaureate or similar.
• Intermediate-higher studies: University Diplomas, Technical Engineering or Teacher Training, Teacher training, Nursing and other studies at the same leve.
• Higher studies: Undergraduate university courses, four-to-six year Degrees, Engineers holding a five-year degree or similar, third-cycle university courses, postgraduate courses, master, doctorate and specialist studies.