America/Edmonton and other zone naming issues

Oscar van Vlijmen ovv at
Wed Feb 8 13:52:42 UTC 2006

> From: "Paul Schauble" <>

> In cases like this I really have to wonder about the custom of using the
> largest city. 
> To me, it makes much more sense to name the entity to which the change
> applies. Not just whatever city happens to be there. Naming the
> province, county, state, or whatever terms the changes applies to
> conveys more information.

The TZ software is Unix driven, so user friendlyness can't be an option ;-)
It's a good thing that the engine itself has the least possible amount of
zones. For maintainability it is a good thing that a zone has a readable
name like America/Denver instead of for instance $937654-ACCF$.

But what about an actual human user?
He/she would think: Boise, that's in Idaho (USA), so he would expect to find
a zone like America/Idaho. But no, he has to use America/Denver, a city
nowhere near Boise and even in another state.
Speaking of Idaho, part of it is in Pacific Time. My guess is that more
people are inclined to couple this to a name like Idaho-West than to

The problem is even worse for let's say Brazil.
One could know that for instance Porto Alegre is in the province of Rio
Grande do Sul in Brazil or Brasil. But to find the correct time you must
realize that Porto Alegre is in America near Sao Paulo, a place not in
America (as in USA) nor in the same province as Porto Alegre.

Europe versus Asia is another issue. Some countries are put into Asia,
others into Europe, but a casual user can only think of e.g. Georgia.
Instead he has to realize that it is in Asia and that the largest place is

The TZ software has probably a fine mechanism for setting up userfriendly
zone names. See the 'backward' file with all its Links.
Virtually nothing has to change in the TZ engine, other than letting a
single zone name (e.g. Georgia) being a valid zone name (instead of

In October 1993 one discussion started around a new zone naming mechanism.
A quote:

    "Of course we should maintain links to traditional names like
    `Japan' and `US/Eastern' for backwards compatibility."


More information about the tz mailing list