Regnal number

Ordinal numbers used to distinguish among persons with the same name who held the same office

Regnal numbers are ordinal numbers used to distinguish among persons with the same name who held the same office. Most importantly, they are used to distinguish monarchs. An ordinal is the number placed after a monarch's regnal name to differentiate between a number of kings, queens or princes reigning the same territory with the same regnal name.

This keyword could refer to multiple things. Here are some suggestions: