[tz] Amsterdam timezone prior to 1937 incorrect?

Paul Eggert eggert at cs.ucla.edu
Tue Sep 6 17:35:16 UTC 2022

On 9/5/22 14:34, Loek Engels via tz wrote:
> Between 2022a an b the timezone info for Europe/Amstedam is removed:
>       Z Europe/Amsterdam 0:19:32 - LMT 1835
> The timezone info for Brussels around that date differs from Amsterdams timezone info.

In the default build Europe/Amsterdam is now a link to Europe/Brussels 
as the two locations have identical timestamp histories since 1970 (the 
tzdb cutoff).

The old Amsterdam data is still present in the file 'backzone'. You can 
use that data by editing the Makefile (see below). However, even with 
the old data Amsterdam timestamps will still be slightly incorrect 
before 1937 due to limitations in tzcode and the tzdata format.

Here's the Makefile section in question.

# If you want out-of-scope and often-wrong data from the file 'backzone',
# but only for entries listed in the backward-compatibility file 
zone.tab, use
#    PACKRATDATA=    backzone
#    PACKRATLIST=    zone.tab
# If you want all the 'backzone' data, use
#    PACKRATDATA=    backzone
# To omit this data, use

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