[tz] Dealing with Pre-1970 Data

Paul Eggert eggert at cs.ucla.edu
Mon Sep 2 06:56:22 UTC 2013

Guy Harris wrote:

> If it's an entry for Paris, rather than for the French time zone,
> why don't we have entries for Lyon and Lille and ...

It's because of the 1970 cutoff.  We would have
entries such as you describe, if we changed the cutoff
to (say) 1940 rather than 1970.  Europe/Paris would split
into 28 zones (if we accept the Shanks data), each with
its own timestamp history.  But the entry for Europe/Paris
itself would not need to change.  So, in the sense of
surviving zone splits better, Europe/Paris is more
an entry for Paris than it is an entry for all of France.

I agree that the LMT offsets are notional, but even so,
requiring them to be multiples of an hour feels ahistorical.
Before standard time was observed people simply didn't set their
clocks to hour-multiples offsets, and it would be odd
to pretend that they did.

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