Exergue on a coin of Carus

ColinCMR

The exergue is KAB

The handbook of Romn Imperial Coins lists KA as a mint in Arelate. Is this an eastern or western mint, does the Greek letter B make sense for the officina #?

CIVITAS

During this period, the mint mark KAB is actually from Rome. They often used greek letters for mintmarks and officinae during the middle to late 3rd century. B is still the officina letter in this case.

ColinCMR

Cool, thanks CIVITAS!