TZ corrections

Paul Eggert eggert at CS.UCLA.EDU
Fri Apr 29 08:01:02 UTC 2005

Jesper Norgaard Welen <jnorgard at> writes:

> For the Palmer station in Antarctica, the rule ArgAQ has been
> declared.  But the rule ArgAQ is not used until 1965, while the rule
> is defined for year 1964.

My intent here was for ArgAQ to be a clone of the useful subset of
Arg.  It's a bit easier for me to test whether they're in sync if the
lines are identical other than the labels Arg, ArgAQ, like this:

Rule    Arg     1964    1966    -       Mar      1      0:00    0       -
Rule    ArgAQ   1964    1966    -       Mar      1      0:00    0       -

EUAsia and E-EurAsia are similar.

> In the Argentina timezones, it seems that apart from the initial LMT
> (which is of course different), the Catamarca timezone and the Chubut
> timezone are in fact identical, so I suggest:

Wow, that was a mistake.  Thanks for catching this.  Catamarca is
bigger, so I'll remove America/Argentina/ComodRivadavia (actually,
move it to the "backward file").

> As far as I can see, the 1949-part of the PRC rule doesn't actually have
> any effect, so it could be deleted:

Thanks.  I vaguely recall that was present to work around an old zic
bug.  There's little point keeping it around any more.

> Unles my interpretation is wrong, both before and after the rule
> takes effect in April 2, 1945, the time in Denmark would be GMT+2
> (e.g. GMT+1 +1)

No, because Rule C-Eur said Denmark stopped observing DST on 1944-10-02.

> As a side-question, I haven't been able to check this with any Time
> Zone Converter (the web version has a cutoff date of 1970). Is there
> any way to check this by a program, and which?

I use zdump (from tzcode) compiled on Solaris.  GNU/Linux would work
too I think.

> The page says that
> the law was in effect from 1. January 1894, not from April.
> The page
> confirms this

Thanks for catching that.  Shanks agrees with that.  I had gone with
Whitman, but it's quite clear Whitman and I were mistaken.

Does either reference say what time-of-day that Standard Time was
introduced?  In the US, for example, the transition occurred at 12:00
new time (not old time).  This leads to interesting lines like this:

# Zone  NAME            GMTOFF  RULES   FORMAT  [UNTIL]
Zone America/New_York   -4:56:02 -      LMT     1883 Nov 18 12:03:58

> in another related law, the effecting DST changes are stated
> explicitly: to be from of April 1980 at 2.00 to of
> September 1980 at 2.00.  If this is true, this differs slightly from
> the EU rule in that DST runs to 2.00, not 3.00.

It would have been odd for the 1980 transitions to disagree with both
old Danish tradition (1945-1948) and with the then-current EU rules.
For now, how about if we assume that the 02:00 of the above source
refers to standard time, not wall-clock time, and so the EU rules were
in effect?

> This in effect confirms the information from Shanks, although there
> is a discrepancy for 1940-1942.

Hmm, sorry, I don't see the discrepancy.  That source says DST was in
effect from 1940-08-11 to 1942-11-02.  Shanks gives 1940-08-10 23:00
to 1942-11-02 03:00.  These pretty much agree.  Norway's rules were
under German control at the time, so it's reasonable to use C-Eur
rules (same as Germany) for that period.

Thanks again for your detailed comments.  I'll submit patches along
the lines described above in my next patch proposal.

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