• Data reference period
• Place of residence (City, NUTS - 2013)

• RESIDENT POPULATION:  The persons who regardless of the fact that at the moment of observation ' 0:00 a.m. of the reference day ' are present or absent in a given housing unit, this unit being where they live during most of the year with their family, or where they have all or most of their belongings.
• ILLITERATE:  Person aged 10 or over who cannot read or write, i.e. who is unable to read and understand a written sentence or write a complete sentence.
• REFERENCE PERIOD:  Period to which the information refers and which may be a specific day or a time interval (month, fiscal year, calendar year, among others).

(Resident population with 10 and more years old ("It does not know to read or write")/ Resident population with 10 and more years old)*100