• Data reference period
• Place of registration (NUTS - 2002)

• NATIONALITY:  A person's legal citizenship at the moment of observation; account is taken of the nationality as in the identity card, passport, residence permit or the certificate of nationality. The persons who at the moment of observation have a pending process for the granting of nationality should be considered as having the nationality previously held.
• MARRIAGE:  The contract entered into by two persons of the opposite sex that intend to found a family in partnership and cohabitation.
• PLACE OF REGISTRATION:  The location of the registry office where a birth, marriage or death was recorded. In the case of a divorce, it is the registry office or court of law where it was decreed.
• 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).

[Marriages between persons of portuguese nationality and foreign nationality (extracommunitarian countries)/ Total of marriages]*100