DefaultApplicationGroup refers to ApplicationInstanceCertificates, what are OPC UA certificates. The DefaultApplicationGrpoup is mandatory. Non OPC UA applications has other certificate types.

We discussed that already in the security WG meeting on 20th of August 2025. The attached word document containing the proposal is also stored in the meeting minutes folder of that meeting.

For PROFINET we need that change urgent, so I hope we can fix that in the 1.05.06 Version of part 12.
(I cannot set the target Version to 1.05.06, also product version 1.05.05 is not in the drop down list, so I write that here)