This is an important thing to learn about rules in numismatics (or life in general?). Below is the #2 item on my want list: Very Rare Caesarea Issue for Niger CNG 99, Lot: 669. Estimate $3000. Sold for $3250. This amount does not include the buyer’s fee. Pescennius Niger. AD 193-194. AR Denarius/Drachm (19mm, 2.89 g, 11h). Caesarea mint. IMP CΛES • C PESCE NIGER IVST • ΛVC, laureate, draped, and cuirassed bust right / ΔHMΛPX I CΞ (sic) VΠΛTOC, calathus containing three grain ears; CT Λ (date) in exergue. Cf. T.V. Buttrey, "The Denarii of Pescennius Niger,” NC 152 (1992), p. xix, fig. 6 (for rev., but with traditional-style portrait); cf. CNG E-320, lot 457 (same). EF, porous. Very rare. The obverse die is for a Latin language denarius. The reverse is a Greek language drachm. Both were in production at the Caesarea mint. Stuff happens. For the record, #1 on my want list is a denarius Septimius Severus overstruck on a coin of Pescennius Niger (extra points if it is one of these mixed language coins) with CLEAR undertype allowing full ID and Septimius dies known to be from one of his official mints. This can be any grade (good is better than poor but we can not be too picky) as long as it fits the 'CLEAR' requirement. I would prefer it not be over Fine just to keep down the price I would have to pay but that is really getting too picky. Close does not count (or I would be happy with the one below) and multiples could be accepted (got a roll?). Yes, I spend a lot of time being 'satisfied' in this hobby. 'Thrilled' is a mite harder to achieve. This thread has seen many very good responses. I hope it will serve many people with differing levels of 'exception' tolerance. One could make a nice mini-collection showing just one example from each of the sub-categories from the link TIF posted: https://rpc.ashmus.ox.ac.uk/introduction/whatisrpc
I believe this article from Forum Ancient Coins gives the simplest explanation and differences regarding the classification of "Provincial" coinage: https://www.forumancientcoins.com/numiswiki/view.asp?key=roman provincial or greek imperial