Please, if you made, make or going to make software which works with dates in ISO 8601 format, remember this:

1. YYYYMMDDThh:mm:ssTZD
2. If it has Z in the end: 20050109T01:44:10Z then the time is UTC.
3. If it has a timezone in the end: 20050109T04:44:10+03:00 then the time is local time.
4. The time on your server is not necessary the UTC time.
5. Test it with different time zones!

Thanks for your attention. Have a nice rewriting.