Chargé d’Affaires

A chargé d'affaires (French pronunciation: ​[ʃaʁʒe dafɛʁ]), often shortened to chargé (French) and sometimes to charge-D (abbreviated in colloquial English), is a diplomat who heads an embassy in the absence of the ambassador. The term is French for "charged with (in charge of) matters". A female diplomat may be designated a chargée d'affaires, following French declension.

A chargé enjoys the same privileges and immunities as a regular ambassador. However, chargés d'affaires are outranked by ambassadors and have lower precedence at formal diplomatic events. In most cases, a diplomat would only serve as a chargé d'affaires on a temporary basis in the absence of the ambassador. In unusual situations, a chargé d'affaires may be appointed for an indefinite period, in cases where disputes between the two countries make it impossible or undesirable to send agents of a higher diplomatic rank.

Chargés d'affaires ad interim ("a.i.") are those who temporarily head a diplomatic mission in the absence of the accredited head of that mission. It is usual to appoint a counsellor or secretary of delegation to be chargé d'affaires ad interim, and he is presented to the foreign minister of the receiving state by the former head of mission before he leaves his post. Chargés d'affaires ad interim are not themselves deemed to be formally accredited, as they do not possess diplomatic credentials.

Chargés d'affaires en pied are appointed to be permanent heads of mission, in cases where the two countries lack ambassadorial-level relations. They are appointed by letters of credence from the foreign minister of the sending state to the foreign minister of the receiving state. Chargés d'affaires en pied have precedence over chargés d'affaires ad interim, but are outranked by ambassadors. They are sometimes referred to as chargés d'affaires ad hoc or en titre.

...
Wikipedia