His/Her Ducal Serene Highness (abbreviation: HDSH) was a style used by members of certain ducal families, such as those of Nassau, Braganza, and the Ernestine duchies (until 1844).
The term "His/Her Royal Highness" (HRH) is a style used by members of certain ducal families, such as those of Nassau, Braganza, and the Ernestine duchies until 1844.