other European courts. The Congress of Vienna finally put an end to these disputes over precedence. After an initial attempt to divide countries into three ranks faltered on the question of which country should be in each rank, the Congress instead decided to divide diplomats into three ranks. A fourth rank was added by the Congress of Aix-la-Chapelle (1818). Each diplomatic rank had precedence over the lower ranks, and precedence within each rank was determined by the date that their credentials were presented. The papal nuncio could be given a different precedence than the other ambassadors. The Holy Roman Empire had ceased to exist in 1806, so the Austrian ambassador would accumulate seniority along with the other ambassadors. Bilateral diplomacy In modern diplomatic practice, there are a number of diplomatic ranks below Ambassador. Since most missions are now headed by an ambassador, these ranks now rarely indicate a mission's (or its host nation's) relative importance, but rather reflect the diplomat's individual seniority within their own nation's diplomatic career path and in the diplomatic corps in the host nation: Ambassador (High Commissioner in Commonwealth missions to other Commonwealth countries); ambassador at large Minister Minister-counsellor Counsellor First secretary Second secretary Third secretary Attaché Assistant attaché The term attaché is used for any diplomatic agent who does not fit in the standard diplomatic ranks, often because they are not (or were not traditionally) members of the sending country's diplomatic service or foreign ministry, and were therefore only "attached" to the diplomatic mission. The most frequent use is for military attachés, but the diplomatic title may be used for any specific individual or position as required, generally related to a specific or technical field. Since administrative and technical staff benefit from only limited diplomatic immunity, some countries may routinely appoint support staff as attachés. Attaché does not, therefore, denote any rank or position (except in Soviet and post-Soviet diplomatic services, where attaché is the lowest diplomatic rank of a career diplomat). Note that many traditional functionary roles, such as press attaché or cultural attaché, are not formal titles in diplomatic practice, although they may be used as a matter of custom. Multilateral diplomacy Furthermore, outside this traditional pattern of bilateral diplomacy, as a rule on a permanent residency basis (though sometimes doubling elsewhere), certain ranks and positions were created specifically for multilateral diplomacy: An ambassador-at-large is equivalent to an ambassador and assigned specific tasks