Thank you for the question.
For the time being we have only the classical way of determining whether a person has overstayed his or her visa, and that is a stamp in the passport, which allows us to actually control, if the passport is available, whether the person is overstaying or not.
In general, with the introduction of the aforementioned visa information system, we will be able to identify people via biometric identifiers and to find out whether someone has overstayed a visa. This was one of the main reasons for introducing this system: to be able to identify people without passports, because usually undocumented or irregular migrants do not present their documents. This will be the first possibility for us to identify people without documents, using biometric identifiers.
There is still a gap, and there are political discussions at the European level now on a planned entry-and-exit system, as the visa information system will cover only those who have applied for a visa, those who have entered illegally, or those whose visa has been waived. For this group of people we are not in position, for the time being, to identify who the person is and whether the person is undocumented or their residence is legal. Of course, if there is no documentation that will indicate to us that the residence is illegal, but it will be difficult to identify the nationality or the identity.