It is on the basis of these features of the officina marks and the bust styles that three series of issues have been identified.* The first issue shows Gallus cuirassed only, with a fine style portrait, and with officina marks only on the obverse; the second issue is the same but uses officina marks on both sides of the coins; the third issue is the most common and features Gallus draped and cuirassed with a coarse style portrait and officina marks on both obverse and reverse. There are a few issues of Antioch that feature no officina marks at all, such as the common MARTEM PROPVGNATOREM reverse type, but most types do. This coin from my collection is of the third series: it features a draped and cuirassed bust with a course style and officina marks on both obverse and reverse. These officina marks consist of a series of dots or Roman numerals indicating any of seven officinae. Trebonianus Gallus, AD 251-253. Roman AR antoninianus, 3.54 g, 20.7 mm, 5 h. Antioch, first officina third series, AD 252-253. Obv: IMP C C VIB TREB GALLVS P F AVG, radiate, draped and cuirassed bust, right; • below. Rev: AEQVITAS AVG, Aequitas standing left, holding scales and cornucopiae; • in exergue. Refs: RIC 80; Cohen 6; RCV 9623; Hunter 52; ERIC II 30 var. (different officina marks). In contrast, here is an example of the first series, with a cuirassed bust and officina marks only on the obverse (Rauch Auction 81, lot 586, 21 Nov., 2007): Here is an example of the second series, with a cuirassed bust and officina marks on both obverse (off flan) and reverse (Naumann Auction 74, lot 423, 03 Feb., 2019): A bit about the reverse type: This reverse type is unique to the Antioch mint on coins of Trebonianus Gallus, though it was used for his son Volusian at the mint in Rome (e.g. RIC 116). Aequitas, the Roman counterpart to the Greek Dikaiosyne, was the personification of equity and fairness, particularly in commerce and business. She is similar to Justitia in her iconography, but Justitia was the personification of justice and fairness in legal matters. Justitia does not appear on the coins of Trebonianus or Volusian. Aequitas is almost always represented as a female figure, clothed in the stola, generally standing but occasionally seated, holding a pair of scales, or very rarely a patera or branch in the right hand, and in the left a cornucopiae or scepter. Some numismatists consider the scepter-like object to be a pertica (measuring rod), which makes sense as a counterpart to the scales as an object for measuring items in the course of commercial transactions. On the coins of Gallus and Volusian, she only appears standing left and holding scales and cornucopiae. ~~~ *Metcalf, William E. “THE ANTIOCH HOARD OF ANTONINIANI AND THE EASTERN COINAGE OF TREBONIANUS GALLUS AND VOLUSIAN.” Museum Notes (American Numismatic Society), vol. 22, 1977, pp. 71–94. JSTOR, www.jstor.org/stable/43573549. Accessed 22 Dec. 2020.