Countermark

https://rpc.ashmus.ox.ac.uk/countermark/804 
GIC 682
Π
incuse 
3.5 x 4.2 mm 
P(rostanna). Appears etched, rather than applied by a punch 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC V.3, — (number not assigned), type ID 75085 Show 759 2 5.3
RPC V.3, — (number not assigned), type ID 75085 Show 759 1 5.3
RPC V.3, — (number not assigned), type ID 75050 Show 746 11 5.3
RPC V.3, — (number not assigned), type ID 75080 Show 753 3 5.3