Marcus Cocceius Nerva was the thirteenth Roman emperor (when elderly: 96-98 AD), the first of the so-called five "good" emperors (Nerva, Trajan, Hadrian, Antoninus Pius, Marcus Aurelius), and the last strictly Italian emperor. See generally J.B. Campbell in OCD(4) s.v. Nerva; De Imperatoribus Romanis entry by David Wend at web address 1.
[1] Compare generally Revelation 1.9 and Eusebius, Ecclesiastical History 3.23.6; neither source names Nerva, though Eusebius notes that the release from Patmos came after the death of Domitian. On John the Evangelist and Patmos, cf. iota 461.
[2] Manes or Mani is the name of the founder of the Gnostic sect called the Manichaeans. The origin of this doctrine in Babylonia is usually dated to the third century AD, not during the reign of Nerva. See mu 147, mu 149, epsilon 3782, kappa 2174.