Countermark

https://rpc.ashmus.ox.ac.uk/countermark/698 
GIC 572
ϚΑϹ (or possibly ϚΑƐ)
rectangular 
8 x 4 mm 
The first letter may be a stigma. The A may be barred orunbarred. The interpretation is uncertain. 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC IV, 6272 (temporary) Show 2227 10 4.3
RPC IV, 9109 (temporary) Show 2198 3 4.3
RPC III, 3797 Show 3797 30 3
Show 112
Show 92
Show 250
Show 282
RPC III, 3796 Show 3796 11 3
Show 389