The exergue is the lowest part of a coin, divided from the rest by a horizontal line. It is usually found on the reverse; seldom on the side of the head and the words or letters form a straight line, while the rest of the legend is placed circularly. In coins of Roman Republic and Early Empire, the exergual inscriptions mark either Consular dates, or Senatorial authority (S C), or more frequently it directly applies to the subject on the reverse. In the late Roman and Byzantine periods, letters generally occupy the exergue which generally serve to indicate the cities in which they were struck. See below:
This coin has "SMANTE" in its exergue, which stands for Sacra Moneta (sacred money) ANTioch (mint) E (5th officina).