The fields (68-70) are filled for those who are more than (10) years old, excluding the students who were born in 1987 or earlier.
68. Persons without certificate
 1 Reading and writing
 2 Reading only
 3 Illiterate
NIU (not in universe)
Reading and writing
Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.
68. Without a certificate:
This field is filled for all persons of a household (male and female) those who are 10 years old or more (they were born in 1987 or earlier) except the students who were still studying and data were taken on them in the fields (65, 66, 67) if the person neither reads or writes in any language is counted illiterate and the sign is put in the square opposite to the word (illiterate).
The person who is unable to read or write numbers or his name, is counted illiterate. If the person reads only and understands what he is reading in any language the sign (x) is indicated in the square opposite to the phrase (reading only). If the person reads and understands what he is reading in any language and writes at least one paragraph in any language the sign (x) is indicated in the square opposite to the phrase (reading and writing).
This variable indicates whether the person is literate or not.