Here is my Constans ae3 Obv.: DN CONSTANS PF AVG, pearl diademed draped bust rt. FEL TEMP REPATIO, Constans standing left on galley, holding phoenix on globe and holding a Chi-Rho on banner; Victory sits at the stern, steering the galley. S 3973var and I think it is RIC VIII 199v. Siscia Mint (BSIS?); is it a backwards R maybe? Check out the detail of the reverse. The celetor fit a lot in very small space!
Good detail TJ, but I can't tell the control mark either. Take a look on Helvetica's. There are some special symbols associated with the Siscia mint.
The first R in REPARATIO sure does look backward, but that means the punch would have been engraved that way, so there might be other examples from the same officina? Very nice coin.