A date or time or both
time

The time element is used to mark a date or time within a sentence.
It provides a way to specify a computer-readable time, for calendaring or other uses, while giving the reader the same time in the vernacular.
Properties
- datetime
- The datetime attribute defines the time in one of these computer readable formats:
YYYY
YYYY-MM
YYYY-MM-DD
MM-DD
YYYY-Www
(year and week)hh:mm
hh:mm:ss
hh:mm:ss.mmm
(time with milliseconds)YYYY-MM-DDThh:mm:ss.mmm
YYYY-MM-DDThh:mm:ss.mmmZ
(UTC time)PhhH
(duration in hours)PmmM
(duration in minutes)PssS
(duration in seconds)
Examples
The year <<time *datetime=2000 2000>> was a leap-year, and
<<time *datetime=2000-02-29 February 29th, 2000>> was only the
second quadricentennial leap day ever, the first and only other one
occurring in <<time *datetime=1600-02 February of the year 1600>>.