About W3C-DTF date and time
W3C-DTF is a date and time notation format defined by W3C NOTE-datetime. A subset limited to only some formats of ISO 8601.
The date and time are connected by "T" and written. The time zone is expressed as "+09:00" as the difference time from UTC, and in the case of UTC, it is expressed as "Z".
Separate seconds and milliseconds with a dot (.).
W3C-DTF is used as a date and time notation for HTTP headers and RSS.
For example, converting January 23, 2000 1:23:45.678 (JST; +09:00) to W3C-DTF results in the following: