And of course "the fractional scale is not unique to US Customary Units", since there is no fractional scale within that measurement system. Nor within any other, AFAIK. Your pound consists of an integer number of ounces (right?) and your foot of twelve-point-zerozerozero... inches. The "fractional scale" exists only between measurement systems. (AFAIK. Except maybe old British currency, that was really weird, I'd trust those crazy Englanders to have about six Pi pennies to the shilling or something.)