What is the X in X-mas?
a title, proper in modern times for members of the house of Habsburg. The title of archduke Palatine (Pfalz-Erzherzog) was first assumed by Rudolf IV, Duke of Austria, on the strength of a forged privilege, in the hope of gaining for the dukes of Austria an equal status with the electors of the Holy Roman Empire. The emperor Charles IV refused to recognize the title, and it was not juridically held by the Habsburgs until 1453, when the emperor Frederick III, a Habsburg, confirmed Rudolf 's privilege and granted the title of archduke of Austria to his son Maximilian and his heirs. All males of the house of Habsburg bore this title; their daughters and wives were archduchesses. The title of archduke or archduchess of Austria also occurred in the royal style of the Bourbon kings and queens of Spain, though they were not descended in the male line from their Habsburg predecessors.