Use the time facet both for how people think
about and reckon time, and for specifying periods
and events. To indicate a specific date and time
or a range of dates, use the international
standard date and time notation.
For dates, use YYYY-MM-DD where YYYY is the year
according to the Gregorian calendar, MM is the
month of the year, represented from 01 (January)
to 12 (December), and DD as the day of the month
between 01 and 31. See International Standard
ISO 8601 for more detail.