The diplomatic corps or corps diplomatique is the collective body of foreign diplomats accredited to a particular country or body.
The diplomatic corps may, in certain contexts, refer to the collection of accredited heads of mission ( ambassadors , high commissioners , and others) who represent their countries in another state or country. As a body, they usually only assemble to attend state functions like a coronation , inauguration , national day or State Opening of Parliament , depending on local custom. They may also assemble in the royal or presidential palace to give their own head of state 's New Year greeting to the head of state of the country in which they are based.
The term is sometimes confused with the collective body of diplomats from a particular country—the proper term for which is diplomatic service . The diplomatic corps is not always given any formal recognition by its host country, but can be referenced by official orders of precedence .
In many countries, and especially in Africa, the heads and the foreign members of the country offices of major international organizations ( United Nations agencies, the European Union , the International Committee of the Red Cross , agencies of the African Union , etc.) are considered members—and granted the rights and privileges—of the diplomatic corps.
Diplomatic vehicles in most countries have distinctive diplomatic license plates , often with the prefix or suffix CD , the abbreviation for the French corps diplomatique .
Dean of the Diplomatic Corps
In some countries, the longest-serving ambassador to a country is given the title Dean, or Doyen, of the Diplomatic Corps and is sometimes accorded a high position in the order of precedence . In New Zealand , for example, the dean takes precedence over figures such as the deputy prime minister and former governors-general . 
Role of the papal nuncio
In many countries that have Roman Catholicism as the official or dominant religion, the apostolic nuncio holds the decanate and is the corps' spokesman on formal occasions; in other cases, the nuncio is treated as an ordinary ambassador of the Holy See and has no special precedence. The Congress of Vienna and the Vienna Convention on Diplomatic Relations provided that any country may choose to give nuncios a different precedence than other ambassadors.  The diplomatic corps may also cooperate amongst itself on a number of matters, including certain dealings with the host government. In practical terms, the Dean of the Diplomatic Corps may have a role to play in negotiating with local authorities regarding the application of aspects of the Vienna Convention on Diplomatic Relations and diplomatic immunity , such as the payment of certain fees or taxes, since the receiving country is required "not to discriminate between states". In this sense, the dean has the role of representing the entire diplomatic corps for matters that affect the corps as a whole, although this function is rarely formalized.
In a final protocol on Article 3 of the concordat between Germany and the Holy See from July 20, 1933, Germany – despite having no official religion and an approximately equal share of Catholics and Protestants – guarantees this role to the apostolic nuncio.
In Belgium the Nuncio has an important position at court, given precedence before the Prime Minister of Belgium , the President of the European Parliament , and the Secretary General of NATO . The only persons who have a higher rank at court are the Cardinals and the members of the Royal family. He acts as such during royal cermonial at court, during Te Deum, annual reception and the national holiday.