[tz] Dealing with Pre-1970 Data

David Patte ₯ dpatte at relativedata.com
Fri Aug 30 11:41:48 UTC 2013

On 2013-08-30 5:43, Stephen Colebourne wrote:
> On 30 August 2013 03:44, David Patte ₯ <dpatte at relativedata.com> wrote:
>> My own preference would be that historical (and perhaps all tz data) be
>> given a numberic identifier, not a 'America/Someplace' name, for the
>> populated areas in question. A good source of geographic identifiers already
>> available is the geonames database. The tz data for Montreal could be
>> identified by the geonames number for Montreal, and the tz data for Toronto
>> associated with the geoname number for Toronto.
>> Then, to build regions, since all geonames records already have a field for
>> the tz region, these could reflect the numeric identifier of the tz
>> recommended region for each location. For example, Ottawa, in the geonames
>> database would refer to the numeric identifier of Toronto instead of
>> 'America/Toronto', until sometime decides to add historical data for
>> Ottawa's own tz history, at which point it would adopt the identifier for
>> Ottawa.
> For the record, such a numeric system would be unacceptable to my
> user-base of developers, who need to include time-zone strings in
> configuation systems, initialization code and test cases. The IDs we
> have are relatively stable and well-known to developers, and the wider
> set of computer-aware people.
> If there were an ID change (which I don't want) I would argue for
> ISO3166/BiggestCity, such as GB/London. Note that such an approach
> allows for two IDs for the same city, useful in the middle east.
> Stephen

I agree with you that user-identifiable zonenames are easier for users, 
and in that case I also prefer ISO3166/BiggestCity - such as CA/Ottawa

The LMT doesnt need to be in the database since thats easily discernable 
by the longitude available from various sources, but the advantage of 
using geonames ids, is that the database supports not only point 
locations (with latlng), but also larger regions, allowing the 
association of tz data with a province or country if it is valid for the 
complete region.


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