[tz] Dealing with Pre-1970 Data

Paul Eggert eggert at cs.ucla.edu
Mon Sep 2 14:16:12 UTC 2013

Lester Caine wrote:
> MY proposal is that if the database returns LMT then it is a flag
> that we are working with 'pre standard time' dates

OK, although that's a different timestamp than the one Guy Harris
was talking about.  Guy Harris suggested a timestamp such that
all clocks in the named region agree after that timestamp, and
some disagree earlier.  For Europe/Paris that would be some timestamp
in 1945, I expect; that information is not in the database now, and
although a number could be deduced from the Shanks & Pottenger
data it'd be almost certainly incorrect.  You want a timestamp
such that time stamps before that date are LMT.  For Europe/Paris
that's a timestamp in 1891, which *is* deducible from the current
database, and which is relatively reliable, at least for Paris.
You should be able to implement the flag that you want,
by consulting the current database.

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