[tz] What is LMTZ?

Lester Caine lester at lsces.co.uk
Fri Sep 20 10:28:35 UTC 2013

Clive D.W. Feather wrote:
>> If somebody wants to establish a Big Database of all changes in time and date reckoning, not just establishment of standard time and rules for changes from standard time, I have no problem with them doing so; I just don't think the tzdb should be that database, even if whoever establishes that database chooses to use the tzdb as part of their database (thus becoming a user of the database).
> Seconded.

 From which the data for TZ should be extracted ... if that is the way forward.
So we are all working with the same set of data.

>> >	In the long term, think that the tz project should attempt to provide as much high-quality data as is reasonably feasible, and that users of the tz data should have the ability to "winnow" and install only a subset of the data.  Here, users of the tz data includes OS vendors, appliance vendors, other software projects, software packagers, system administrators, and end users.
>> >
>> >so that the tzdb can have historical data about standardized time*but*  should offer tools to allow users, in his sense, to discard historical data if it imposes what those users deem significant costs in excess of what they deem the benefits.
> I think this is a good objective.

Just to reiterate here why *I* found a problem. The PHP timezone tools return 
the daylight saving settings for the 2nd world war period, and there were some 
discrepancies that needed explaining. At that time I had no idea that TZ was NOT 
providing the right data pre-1970 but I can now see that simply by a fluke I was 
getting the necessary material. If distributions are now going to be including 
or excluding this information at leisure then we need some big flags saying if 
the returned information is correct or not. i.e. if winnowing results in 
different pre-1970 data then there is a big potential hole! THIS is why we need 
to understand just what is being proposed and what the results will be. That 
some of the current material is suspect is a red herring ... providing 
consistent auditable material would create a problem if winnowing then hides 
that data? Some users get one answer some another ...

Lester Caine - G8HFL
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