What's the difference between i.e. and e.g.?
in ancient Rome, a provisional ruler specially appointed for a period during which the normal constituted authority was in abeyance (the interregnum). The title originated during the period of the Roman kings when an interrex was appointed (traditionally by the Senate) to carry on the government between the death of one king and the election of his successor. It was subsequently used in republican times for an officer appointed to hold the comitia that would elect new consuls when for some reason the retiring consuls had not done so