Styles and forms of address Most often, a sovereign grand duke was styled as "Royal Highness" (abbreviated "HRH"), possibly because of the connection of many grand-ducal houses to royal ones or as the highest style beneath that of a king (sometimes styled "Royal Highness"). The heir to the throne (a hereditary grand duke) was sometimes styled as "Royal Highness", otherwise as "Grand Ducal Highness" (HGDH). Junior members of the family also generally bore the lower title of prince or princess with the style of "Grand Ducal Highness". However, in other grand duchies (e.g., Oldenburg), junior members of the family bore the title of duke or duchess, with the style of "Highness" (HH).
Styles and forms of address Most often a sovereign grand duke was styled as "Royal Highness" (abbreviated "HRH") possibly because of the connection of many grand-ducal houses to royal ones or as the highest style beneath that of a king (sometimes styled "Royal Highness") The heir to the throne (a hereditary grand duke) was sometimes styled as "Royal Highness" otherwise as "Grand Ducal Highness" (HGDH) Junior members of the family also generally bore the lower title of prince or princess with the style of "Grand Ducal Highness" However in other grand duchies (eg Oldenburg) junior members of the family bore the title of duke or duchess with the style of "Highness" (HH)