The patent rolls record the issue of letters patent from the reign of King John. The entries on the rolls are of a very diverse nature referring to the royal prerogative, revenue, the differential negotiations with foreign princes and states, letters of protection, of credence and of safe-conduct and the appointments and powers of ambassadors. There are also grants and confirmations of liberties, offices, privileges, lands and wardships, both to public bodies and to private individuals, charters of incorporation and so on. Letters patent are stated to have been much reduced in the course of the 19th and 20th centuries, as the kinds of instruments produced thereby became obsolete or their administration passed to other bodies. The use of great seals was much restricted, often replaced by alternative devices.