Has the data been pseudonymised but there is a clear mechanism that allows re-identifying individuals?
E.g. names and addresses have been removed before the data was handed to you but the organisation that performed the pseudonymisation has additional data that, matched with the data you have, allows identifying individuals
Yes, the data has been pseudonymised and only pseudonymised
No, the data has undergone other or further anonymisation processes
I'm not sure, what is pseudonymised data?
Personal data from which directly identifying information has been masked or hidden from those receiving the data, but not deleted. Identifiers of a direct type still exist but are stored separately and securely, such that they can only be accessed by authorised persons (usually limited to staff of the data provider).
In other words, the ‘key’ to match the data to individuals is not in your possession, but it still exists.