Countermark

https://rpc.ashmus.ox.ac.uk/countermark/1141 
GIC 712 .1
ΡΛ
rectangular 
5.5 x 3.5 mm 
GIC 712 had "?A and AS (uncertain letters, two countermarks)". Later examples allow this to be split to a cmk with ΡΛ on it (https://rpc.ashmus.ox.ac.uk/countermark/1141). This appears to have been consistently placed on or about Trajan's ear 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC III, 2911 Show 2911 20 3
RPC III, 2911 Show 2911 5 3
RPC III, 2911 Show 2911 4 3
RPC III, 2911 Show 2911 6 3
RPC III, 2911 Show 2911 15 3
RPC III, 2911 Show 2911 19 3
RPC III, 2911 Show 2911 25 3
RPC III, 2910 Show 2910 8 3
RPC III, 2911 Show 2911 29 3