[tz] Adding verified historic details

Lester Caine lester at lsces.co.uk
Thu Sep 5 13:50:37 UTC 2013

Paul Eggert wrote:
> I agree that changing the format of
> the zic input would make it considerably
> easier to maintain data, particularly
> the mass of pre-1970 data you're thinking
> about.  But someone would need to come up with
> what the new input format actually is, and implement
> that change.
> I expect that we would use the
> new zic-input format only in the new
> "extended" zones that would be excluded
> from typical POSIX installations;
> this should lessen backward compatibility concerns.

I'll put my hand up and admit to not having ever used zic and only looked at the 
manual today. I'm using the PHP tools for looking at 'published' data, and that 
is the calendar that I am expecting to scoll back through the 20th century and 
get correct times. Adding the Jersey and Guernsey data will ensure that for the 
war period is going to be correct in future.

I don't think the proposals I'm making break zic. The new 'Rule1' for LMT only 
requires an additional piece of information from outside TZ and handling the 
relevant date could be moved there. An 'extended' with all of the 'timezones' 
you are worried about - just locations with links to existing rules mainly. 
Personally I don't think that there will be an unmanageable increase in 'rules' 
if we managed to find every documented change pre-1970. It will be things like 
using or not daylight saving, but the extra 'extended' data could be levered to 
add out of sync data.

I hate to say this, but keep zic for creating 'TZ' and develop a new tool using 
the 'extended' data to give a 'TZ+' view.

I've got to the point on my own setup that I'm looking to dump the raw data into 
a database and create code to work with that via SQL calls. A lot more flexible, 
and I already have a comprehensive set of location data in that, which links to 
the OSM mapping.

Lester Caine - G8HFL
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