Not declaring myself as an American or European, but as a
Computer Scientists, why not provide a mechanism for
expressing physical measurements using tags?
Introduce a set of units, and write measurements as pairs
(number,unit) represented in some convenient concrete
syntax. Then the conversion to html can display miles or
kilometers according to the viewer's perspective.
PS. I know I am leaning towards ontologies again, but this is an
example where the benefits seem obvious.
Viktor