In fact, it was not until the late Middle Ages that IV came into use – and when the first mechanical clocks were made, between the 13th and early 14th century, IIII was still in common use.
Occorrerà aspettare fino al tardo Medio Evo perché si diffonda la variante alternativa e, quando vennero realizzati i primi orologi meccanici tra il XIII e il XIV secolo, la notazione antica era ancora ampiamente usata.