[tz] TIme in Belize

[Paul Eggert]

On 11/6/20 1:59 PM, Michael H Deckers wrote:
>> -Zone America/Belize    -5:52:48 -    LMT    1912 Apr
>> +Zone    America/Belize    -5:52:48 -    LMT    1912 Apr  1
> 
> 
>    but the source is quite clear that it should be
>       +Zone   America/Belize   -5:52:43 -   LMT  1912 Apr  1

Unfortunately it's not so clear. Here's a citation to the source:

# Definition of Time Ordinance, 1927 (No.4 of 1927) [1927-04-01]
# Ordinances of British Honduras Passed in the Year 1927, p 19-20
# https://books.google.com/books?id=LqEpAQAAMAAJ&pg=RA3-PA19

It says that standard time was established as -06 on 1912-04-01, and that -06 
was 00:07:17.27 later than the local mean time at Belize. However, by my 
calculations -05:52:42.73 is longitude 88° 10′ 40.95″ W, which Google Maps says 
is in the ocean east of Belize city, so this was not LMT in Belize city.

To my mind what matters here is what was the legal time in Belize city before 
1912-04-01. If there was no law or it was just LMT, no change needs to be made. 
If it was -05:52:42.73 then we need to find out when that legal time was 
instituted (perhaps for all of British Honduras?), and insert a transition from 
LMT to -05:52:42.73 at the appropriate date.

One constraint we like to follow is that the LMT longitude corresponds to the 
longitude in zone1970.tab.