Editing Grand duke (section)

==Styles and forms of address==
Most often, a sovereign grand duke was [[style (manner of address)|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., [[Grand Duchy of Oldenburg|Oldenburg]]), junior members of the family bore the title of duke or duchess, with the style of "Highness" (HH).

The [[Grand Ducal Family of Luxembourg]] styles all its members as "Royal Highness" since 1919, due to their being also cadet members of the [[House of Bourbon-Parma|Royal and Ducal House of Bourbon-Parma]] as male-line descendants of [[Prince Felix of Bourbon-Parma]].

The [[House of Habsburg-Lorraine|Habsburg]] grand dukes of Tuscany, being members of the imperial family of Austria, were styled as "[[Imperial and Royal Highness]]" (HI&RH).

Grand dukes and grand duchesses from Russia were styled as "[[Imperial Highness]]" (HIH), being members of the [[Russian Imperial Family]].