AEIOU, series of vowels which Emperor Friedrich III (1440-1493) commissioned as a decoration on many historical buildings (e.g. St. Ruprecht's Church in Vienna, the castle in Wiener Neustadt, western portal of the Graz Cathedral), on his state carriage, etc. Contemporaries and posterity interpreted it in various ways: "Austriae est imperare orbi universo" (Lat. = It is Austria's destiny to rule the world), "Austria erit in orbe ultima" (Lat. = Austria will exist eternally) or "Alles Erdreich ist Oesterreich untertan" (Ger. = All the earth is subordinate to Austria). This series of vowels may be an expression of the Emperor's magical and mystical formulaic beliefs; however, it mainly demonstrates his belief in the calling of the House of Austria.
Further reading#A. Lhotsky, A.E.I.O.U. Die "Devise" Kaiser Friedrichs III., in: MIOeG 60, 1952.