Question on abbreviations

Andy Lipscomb AndyLipscomb at
Wed Sep 27 20:36:02 UTC 2006

Rules don't expire. Each rule creates a number of transition points--an "only" rule creates exactly one, a ranged rule creates one for each year in the range, and a "max" rule yields an infinite number (in theory). The current DST rule is always the one put in effect by the most recent transition point 

J Andrew Lipscomb, CPA*ABV, ASA

Decosimo Corporate Finance

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-----Original Message-----
From: Paul Schauble [mailto:Paul.Schauble at] 
Sent: Wed 27 September 2006 16:28
To: tz at; tz at
Subject: RE: Question on abbreviations

Then I'm confused. At the end of 1942, that rule should expire, because of the "only" leaving what rule in effect? Apparently none, leaving the time in 1943 undefined.

Where can I find a explanation of the tz text database format?


-----Original Message-----
From: tz-request at [mailto:tz-request at]
On Behalf Of Paul Eggert
Sent: Wednesday, September 27, 2006 9:29 AM
To: tz at
Subject: Re: Question on abbreviations

"Mark Davis" <mark.davis at> writes:

> According to the spec, TO = "only" is equivalent to saying that the TO
> equals the FROM value.

Yes, that's what's happening here.  The rule to switch to DST applies only in 1942.  There is no rule to switch _out_ of DST in 1942, so DST continues until 1945, the next rule that applies.

>> Rule    NAME    FROM    TO    TYPE    IN    ON    AT    SAVE
>> > ...
>> > Rule    US    1942    only    -    Feb    9    2:00    1:00    W #
>> > Rule    US    1945    only    -    Aug    14    23:00u    1:00    P

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