The relative importance of different positions is weighed, and even the date of the position's establishment is frequently considered. Military rank constitutes a clear basis for determining seniority among military personnel. Comparable rank and the date of its attainment will decide the precedence among officers from the different smites, both United States and foreign. By custom, reserve officers are ranked with, but after active duty officers of that same grade. Retired officers are ranked similarly with their precedence following reserve officers of the same grade.
Diplomatic precedence is the result of international agreement.
The precedence of chiefs of missions rests upon the length of their service in that country. An ambassador who arrives and is accredited in April precedes another who arrives and is accredited in November of that same year. An ambassador will always precede a minister who heads a legation. For example, suppose the British Ambassador arrives and is accredited in April of 1980. Because in this case, the British Ambassador outranks the Danish Ambassador, the British First Secretary will outrank the Danish First Secretary.