The FEL TEMP REPARATIO series contains lots of variation. The ouput of Siscia contains a series with some odd symbols in the mintmarks. an example of these symbls is attached below.

Amongst this series is a small group where the coins have started to decrease in size and these symbols appear in the fields instead of in the exe where they usually appear. RIC designates these as common but they seem more difficult to obtain in practice.
I recently managed to obtain a couple and thought it worth sharing them here.
Constans - AE3
Obv:- DN CONSTA-NS PF AVG, pearl-diademed, draped and cuirassed bust right,
Rev:- FEL TEMP-REPARATIO, Nimbate Phoenix standing right on ile of rocks
Minted in Siscia; (_ | Sym2 //BSIS), A.D. 348-350
Reference:- RIC VIII Siscia 247 (C)
0 degrees. 2.59 gms. 19.28 mm
(I suspect that the silvering is not ancient.)

Constans - AE3
Obv:- DN CONSTA-NS PF AVG, rosette-diademed, draped and cuirassed bust right,
Rev:- FEL TEMP-REPARATIO, emperor in military dress standing left on galley, holding Phoenix on globe and labarum, Victory sitting at the stern, steering the ship
Minted in Siscia; (Sym4 | _ //DSIS), A.D. 348-350
Reference:- RIC VIII Siscia 248 corr. (err. in RIC right field instead of left field) (C2)
0 degrees. 2.65 gms. 18.67 mm

Regards,
Martin