Some questions about the database format

Yves Goergen nospam.list at
Tue Jun 29 13:27:01 UTC 2010


I intend to use the tz database in my C# calendar application. Since I
need a decent time zone support, I was pointed to this database from the
MSDN forums. I now have a few questions regarding the file format of the
text files.

A day specification of "Sun>=1" or "Sun>=8" should be clear, I interpret
this as the first/second Sunday in a month. But what weekday and week is
"Sun>=25" or "Sun>=2"?

How is the Zone field "[UNTIL]" to be understood exactly? Is it including
or excluding the given time? What does "1990" mean, is it until and
inclusive the whole year 1990, ie /1990-12-31T23:59:59 or is it something
around 1990-01-01?

What does the time specification "2:00s" mean? I've seen it several times
but couldn't make any sense of it.

Are all rules in the text files sorted ascending by time ("FROM" year)?
That would simplify the processing because in order to convert them into
.NET framework structures I need pairs of DST start and end rules together
for a range of years, and thus need to resolve the overlapping rule

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