Era of the Martyrs
The Era of the Martyrs (Latin: anno martyrum), also known as the Diocletian era (Latin: anno Diocletiani), is a method of numbering years based on the reign of Roman Emperor Diocletian who instigated the last major persecution against Christians in the Empire. It was used by the Church of Alexandria beginning in the 4th century AD and it has been used by the Coptic Orthodox Church of Alexandria from the 5th century until the present.