[tz] Dealing with Pre-1970 Data

[David Patte ₯]

Though it has been handy to have some pre-1970 data within the tz 
database, I don't see that it is the best solution for historical tz 
data in the long run. It is clear that that going back far enough in 
time there is a different LMT for every 15 seconds of latitude.

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.