[tz] How good is pre-1970 time zone history represented in TZ database?

Lester Caine lester at lsces.uk
Wed Jun 3 11:22:32 UTC 2020

On 03/06/2020 12:09, Alois Treindl wrote:
> The backzone zones cover only a very small part of the problems we know 
> about.
> Using the backzone prevents using the official tzdata distribution, as 
> one has to compile with special procedures so that backzone data are 
> compiled in.
> This would prevent us from using the official tzdata packages provided 
> automatically for Redhat Enterprise Linux.

THAT has been my own complaint for years ... tzdist at least accepted 
that some rule sets are only valid for a reduced timeframe, and report 
that fact, but as yet there are no sources of this more accurate data as 
yet? A tzdist publisher would have the ability of improving their own 
historic data and in addition flag when rules have changed from when a 
previous normalization was applied. The CURRENT problem is even when 
present day time offsets change, a distribution will simply apply the 
new rules without any flagging that currently stored data may now be 
incorrect. One needs to be able to view the rule used for the stored 
data in parallel with the new rule even if only to flag human 
intervention is needed.

Lester Caine - G8HFL
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