The letter you see has a peculiarity. On the right side, three writings are visible one below the other joined by a parenthesis. In modern times the superscripts or the overcoats bore signs that constituted a sort of visual summary or symbols of the type of communication. They were symbols rich in political, economic and social content. In this envelope, for example, on the right, we find the word cito repeated 3 times: it is the reinforcement of "citissime" (from the Latin "citius") and is nothing more than an incitement to run to go fast or "flying ".