Default time zone for a location (previously Europe/London)
Oscar van Vlijmen
ovv at hetnet.nl
Tue Sep 5 12:03:20 UTC 2006
> From: Paul Eggert
> Subject: Re: Europe/London
Or more appropriately:
> Subject: Re: Default time zone for a location (previously Europe/London)
> "Srdjan Krajnalic" writes:
>> However GB-Eire starts with a 1916 rule, leaving anything from 1847 until
>> 1916 seemingly undefined.
> Until the first rule applies, you use the first-listed rule that
> is on standard time (in this case, "GMT" with UTC offset zero).
> Unfortunately I don't see this point being covered clearly in the
> zic man page.
I believe a similar situation was mentioned by me on 2004-05-17.
If a Zone line gives a DST Rule, but no valid Rule can be found, then what?
The last Rule lines:
Rule ROK 1987 1988 - May Sun>=8 0:00 1:00 D
Rule ROK 1987 1988 - Oct Sun>=8 0:00 0 S
Some Zone lines:
Zone Asia/Seoul 8:27:52 - LMT 1890
8:30 - KST 1968 Oct
9:00 ROK K%sT
For periods starting 1989 there is no valid Rule.
The answer given by 'ado' May 2004 was:
Remember that the Rules tell when DST transitions happen; in the above case,
the Rule that's valid is one that specifies the last transition before May
2004 [read: today], which is assumed to be in effect in perpetuity.
Generally speaking, we want to have the last line of a Zone refer to a Rule
line. This is particularly important in cases where a country has multiple
If the country decides in the future to change the way DST is handled (for
example, decides to start observing DST again), we can make things right by
changing one Rule rather than by changing multiple Zones.
Maybe this repeated information helps writing clarifications for the manual.
More information about the tz