[tz] Converting cities to tz identifiers (tangent)

[Guy Harris]

On Feb 20, 2018, at 4:12 PM, Steve Allen <sla at ucolick.org> wrote:

> On Tue 2018-02-20T15:41:05-0800 Paul Eggert hath writ:
>> As Guy Harris wrote, the whole idea of TZ='US/Eastern' is
>> reasonably fuzzy and there's certainly no expectation of a
>> particular time zone history for it.
> 
> I think a US lawyer would disagree that there is any fuzziness for the
> "time zone" US/Eastern *if* that were defined as in 15USC260 thru
> 15USC263.  The Uniform Time Act of 1966
> https://www.gpo.gov/fdsys/pkg/STATUTE-80/pdf/STATUTE-80-Pg107.pdf
> was passed 1966-04-13 and specified that all local times in the US
> were to be set forward on last Sunday April and back on last Sunday
> October.

...unless some State decides to exempt itself as, for example, the Grand Canyon State currently does.  Some parts of the Mountain time zone change local times in that fashion (as modified by subsequent laws, so no longer April and October), other parts do not.