the ligatures ⟨æ⟩ and ⟨œ⟩ is common in words such as archæology, diarrhœa, and encyclopædia, all of Latin or Greek origin. Nowadays, the ligatures have...

Middle Ages, although at that time ⟨w⟩ was not considered a letter but a ligature of two ⟨v⟩s or ⟨u⟩s). However, in the Ortografía of 1969, RAE included...