Mile unit is another one of the same sort - https://en.wikipedia.org/wiki/Mile with the exception that only two kinds have survived if I'm not mistaken - US mile and nautial mile
I guess it can be very simple in US, especially if mug/cup volumes are defined in terms of a "cup" multiples, but in europe I get totally lost when I see the cup unit in the recipe since I din't know what volume it refers to