Why does a datetimeoffset have 28 hours of timezones?

Question

I am looking into using the datetimeoffset for SQL Server 2008. According to the MSDN article there is a time zone offset range of -14:00 through +14:00. I can understand going 12 hours from UTC in each direction, one hour per timezone. I think I understand 13 hours in each direction, for daylight savings time. I just dont get 14 hours?

Answer 1

Living next to a time-zone border that involved a 20+ hour jump would be very difficult, so political entities near the International Date Line simply define their timezone as extending beyond +/-12 for the convenience of the people living there.

This forces the effective "data flip line" to have a very funny shape but to never affect "neighbors" for a fairly expansive definition of "neighbor". It is only possible because of how sparely populated the Pacific Ocean is.

This is basically the same reason that time-zone boundaries tend to avoid big cities and follow either political boundaries or major geographical features such as big rivers, mountain chains or deserts.

Answer 2

Some places have a timezone offset larger than 12. I can only recall Tonga (+13), but there might be more.

Edit: ah, Line Islands, +14:00 :)

Timezone map on Wikipedia

Answer 3

Christmas Islands are +14:00, see here.