The territory names are hierarchical as in country or country-territory to allow overriding higher level values (for example in the US Virgin Islands there is left hand traffic, so that requires an entry for us-vi). Note the lower level entries do not inherit properties from higher level ones.
Properties:
"distance" unit system for distance and speed "metric" (default) or "imperial"
"left-hand-traffic" side of the road that is driven on, false (default) or true
"speed-limits" array of common speed limits in the territory, if "distance" is "imperial", the units are assumed to be miles per hour, otherwise km per hour
Ideas for additional properties
"vienna-convention" signatory of https://en.wikipedia.org/wiki/Vienna_Convention_on_Road_Signs_and_Signals