[ILUG] the first day of the week?

[Pádraig Brady]

As the following script shows, the locale for IE on linux
has Sunday as the first day of the week. I always think
of Sunday as the last day and the UK locale concurs.
Where could I lookup the "right" answer?

for LANG in en_IE en_GB; do
  date -d"$(locale week-1stday) +$(($(locale first_weekday)-1))day" +%a
done

Sun
Mon