Hi John,
According to the "Vorschrift über das Bezeichnen und Numeriren der ........Waffen" from 1877, Feldartillerie was marked x.A.x.xx and Fußartillerie x.A.F.x.xx to make a clear distinction between the two. It doesn't look like the F.A.R. marking was in use yet.
Why would that be so different for the marking of equipment?
Regards,
Lars