An official proclamation is a formal announcement or statement issued by a governing body. The term can be used to refer to four different types of declarations: a FIAT, a DECREE, an EDICT, and a UKASE. A FIAT is an authoritative order or command issued by a person in power. A DECREE is a law or order issued by a ruler or government. An EDICT is a formal proclamation issued by a sovereign or other authority. Finally, a UKASE is a proclamation or order issued by the Russian tsar or government.