 The title of "metropolitan" was apparently well known by the 4th century, when there are references in the canons of the First Council of Nicæa of 325 and Council of Antioch of 341, though the term seems to be used generally for all higher ranks of bishop, including patriarchs.The term "archbishop" does not appear in the modern sense until the 6th century, although the role, above ordinary bishops but below patriarchs, seems to be established for metropolitans by the 5th century.Episcopal sees are generally arranged in groups in which one see's bishop has certain powers and duties of oversight over the others.