Re: [LEAPSECS] Consensus rather than compromise

From: John.Cowan <>
Date: Wed, 31 Aug 2005 09:16:33 -0400

Mark Calabretta scripsit:

> If such a system were to be adopted, then in future, in order to
> determine a historical time, the full record of timezone changes would
> be needed. For general purposes, a record would have to be maintained
> for every civil administration that sets its timezone (I'm thinking of
> /usr/share/zoneinfo). This would be a much bigger deal than the current
> daylight saving switches.

That's exactly what /usr/share/zoneinfo is for, and even it buries all
historical timezone differences older than the Epoch, which was only 35
years ago. We manage well enough: the total amount of data in binary
form is only 5 MiB, trivial by today's standards.

> Inevitably it also means that the world's timezones would fragment
> as adjacent civil administrations adopted disparate policies on timezone
> adjustment.

Why should they? It's annoying and expensive to be in a different zone
from your neighbors and trading partners, which is why (e.g.) the bits of
Indiana near Chicago and St. Louis are on Central Time and the bits near
Cincinnati and Louisville are on Eastern Time instead of agreeing with
the rest of the state. Not to mention why all of China is on UTC+8h
despite LMT offsets varying from UTC+5h4m (Kashi again) to UTC+8h8m
(Ningbo) and even a little beyond.

I would expect just the reverse to happen: common agreements beyond
national boundaries, as the EU countries have agreed to common DST
transition events but not a common time zone.

> And then, as the political map of the world changes, so
> the record would become ever more hopelessly complicated.

In fact /usr/share/zoneinfo has at least one zone for every country now,
just in case Canada should decide on different DST transitions from the
U.S. or something. (It has done so in the past, anyhow.)

The offset adjustments required to keep TAI-based LCTs roughly in line
with Earth rotation would be no different from what we already deal
with routinely.

By Elbereth and Luthien the Fair, you shall
have neither the Ring nor me!  --Frodo
Received on Wed Aug 31 2005 - 06:18:04 PDT

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