It turns out that a handful of locales (e.g. af_ZA, en_ZA, fa, hr, hu, ja ...) have dates with the form y/m/d.
So it looks like the value for the date component order (and the optional parameter to DT::F::Simple) should be a string that can take the 3 values: 'ymd' 'dmy' 'mdy' Does this make sense? -ben