Question on abbreviations

Mark Davis mark.davis at
Wed Sep 27 21:37:58 UTC 2006

The documentation is in zic.8.txt.

I share your confusion. If Paul (Eggert's) description is right, then I have
to ignore the TO field in some circumstances which are entirely unclear to
me. I would much rather see the TO field corrected. That is, if TO=1942 is
ignored, and 1945 is the real date, then the line should be corrected to

There are other failures in the parsing. My error messages are:

??? Format too short: '' under Europe/Amsterdam;
??? Format too short: 'S' under Europe/Amsterdam;
??? Format too short: '' under Europe/Moscow;
??? Format too short: 'S' under Europe/Moscow;

I looked into why this is happening, and found:

Zone Europe/Amsterdam    0:19:32 -    LMT    1835
            0:19:32    Neth    %s    1937 Jul  1

But the first LETTER/S defined by Neth is in 1916, so during the range from
1835 to 1916 this is undefined. If the LETTER/S are magically also defined
*before* the first FROM, that should be described in the specification.


BTW, the documentation was a first a bit confusing to me, since it says that
fields are delimited by spaces, and lists a single Zone UNTIL field.
However, if you look carefully at the documentation, there are really 4


which are optional [but only in "truncation" from the end: that is, it
corresponds to the (Perl) regex (UNTIL_YEAR (UNTIL_IN (UNTIL_ON

I'm not the only one to have initially made this mistake: the proposed XML
format for the TZ database makes the same mistake.

On 9/27/06, Paul Schauble < Paul.Schauble at> wrote:
> 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?
>   Thanks,
>     ++PLS
> -----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
> value
> > 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 #
> War
> >> > Rule    US    1945    only    -    Aug    14    23:00u    1:00    P
> #
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