"Attestation of Activities" means an official EU form that explains a period when a driver has no tachograph record — for example sick leave, annual leave, or work that isn't driving.
Regulation (EC) 561/2006 and the AETR (the equivalent agreement for international transport outside the EU) recognize it as valid proof for that gap, as long as it's filled in and signed before the journey it covers, and kept together with the driver's tachograph records.
The form has the driver pick exactly one reason for the gap — sick leave, annual leave, other leave or rest, driving a vehicle exempt from the regulation, other work, or simply being available — and confirm they weren't driving a vehicle covered by the regulation during that time. Submitting an attestation that isn't true counts as an infringement in its own right.
