Nice and rare find !
Bastien #444, 8th emission, 3 ex.
I assume that there are a few mistakes or approximations in RIC for this reference #15 :
-There is no known coin for Diocletian from the second workshop. Excepted a coin described by Voetter (see Bastien #628 note 4) but not to be found.
-All known coins are from third workshop.
-There is no known IMP DICOLETIANVS P F AVG (12) legend for the COMES AVGG emission (8th). Excepted the coin described by Voetter.
-#15 & 16 are rated common but the five COMES AVGG types for Diocletian are known by 1 to 5 examples.
-Even if there is a confusion with Maximian's coins, there is only one emission (12th) that has an example for COMES AVGG with MAXIMIANVS P F AVG legend known by only one example (B.628).