 Two sources -- one a military diploma, the other an inscription from Troesmis -- attest Calpurnius Macer as the governor of Lower Moesia; so it is likely he was governor at the time of this letter from the emperor.Werner Eck dates his tenure in this post as extending from the year 110 to 113, noting that a yet unidentified governor served between Macer and Lucius Fabius Justus.Nothing further is known of Macer.