What is "lampadarius"

A lampadarius, plural Lampadarii, from the Latin "lampada" , from Ancient Greek "lampas" λαμπάς ( candle), was a slave who carried torches before consuls, emperors and other officials of high dignity both during the later Roman Republic and under the Empire. Lampadarios in the post- Byzantine period designates the leader of the second (left) choir of singers in the Eastern Orthodox church practice.