^ abA passus is an ancient Roman unit of length that is 2 gradūs. One passus is 1.62 yards (1.48 m). There are 1000 passus in one mille, which was sometimes referred to as a mille passus. A passus was roughly the pace step of a single legionary.
^Lajo Pérez, Rosina (1990). Léxico de arte (in Spanish). Madrid: Akal. p. 134. ISBN9788476004937.