• Data reference period
• Place of residence (Freguesia - at the time of the 2001 Census)

• 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:  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.

(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