Fernet-Branca has been well known around the world as a “digestiv” since about 1845. The above poster shows Fernet-Branca described as a “digestivo.” By contrast, the US label, on the right, bears no reference to this key term.
TTB does not allow any reference to digestif, digestiv or similar. Here is an example of a recent rejection, wherein TTB explains that the term is not allowed, and why. TTB regards it as a therapeutic claim.
Eric Asimov explains:
Digestives were historically intended as palliatives, meant to counter all sorts of ailments and physical imbalances. They may no longer be assigned quite the same medicinal value today as they were a few hundred years ago, but count me among the many who believe they can help to settle that queasy feeling.
Fernet-Branca is one of the more famous examples of a digestif, but there are others, such as Fernet Stock, Escorial, Becherovka, Averna, bitters, amaro, etc. In general, digestifs are intended to be consumed after a meal, with dessert of coffee. By contrast, aperitifs, such as Aperol and Campari, are most often served before meals.