It contains the unique identification of the person (10 characters). As the identification, the birth number (9 character numbers have a space in right) is used, the identification number of organization (IC) is used padded with zeroes on the left to the full length (e.g., input '0000001379' for '1379'). The CDCP assigns alternative identification number (called NID) for foreign persons, Czech legal entities having no identification number or for Czech individuals in case of duplicity.
If the field is not available, the output contains information about all subjects with the security account managed by the requester.