More specific provisions:

Art. 6 II: "Member States may maintain or introduce more specific provisions [...] with regard to processing for compliance with points (c) and (e) of paragraph 1 by determining more precisely specific requirements [...] including for other specific processing situations as provided for in Chapter IX." ► Art. 87 is in Chapter IX.

Further determination:

Art. 87 (1): "Member States may further determine the specific conditions for the processing of a national identification number or any other identifier of general application."