[tz] timezone DB distribution

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Thu Aug 20 19:33:37 UTC 2020

On 2020-08-20 11:34, Michael Douglass wrote:
> On 8/20/20 03:14, Martin Burnicki via tz wrote:
>> I'd really appreciate if tzdist would be more adapted and used.

>>> tzdist server implementations?

>> I think there is at least one implementation available.

> There's at least 3 - either up to date with the spec or close.

I could find nothing of use - care to share the source repos, servers, or sites?

>> What I'm wondering is if there are client implementations that can
>> update the local TZ rules on the fly so that systems that are running
>> continuously automatically start using the updated rules once they have
>> become available.
>>> Leave it to the distro or platform to do the job as quickly as any other
>>> downstream org.
>>> Org update policies may be a bigger delaying factor than tzdb, distro, or
>>> platform.
> Certainly some large organizations are unwilling (currently) to change their
> update policies - treating tz data as system code or being very slow with their
> updates.
> If you want truly up to date tz info you often have to fetch it yourself - which
> is where tzdist could be useful.

>> And what about the IoT stuff and other embedded systems for which there
>> is no distro that is maintained and updated regularly?

They often have bigger issues with space for decoding, data storage, and use;
one suggestion was a stream compressed list of file base names and POSIX strings
from the last line of the files e.g.

	London GMT0BST,M3.5.0/1,M10.5.0\n...

also could reduce the locations to one "airport" code per rule as in watches
(extract from Casio manual):

City			UTC
Code	City		Offset	Other major cities in same time zone

PPG	Pago Pago	–11.0	
HNL	Honolulu	–10.0	Papeete
ANC	Anchorage	–09.0	Nome
YVR	Vancouver	–08.0	San Francisco, Las Vegas,
LAX	Los Angeles	        Seattle/Tacoma, Dawson City, Tijuana
YEA	Edmonton	–07.0	El Paso, Culiacan
DEN	Denver		
MEX	Mexico City	–06.0	Houston, Dallas/Fort Worth, New Orleans
YWG	Winnipeg	
CHI	Chicago		
MIA	Miami		–05.0	Montreal, Detroit, Boston,
YTO	Toronto		        Panama City, Havana, Lima, Bogota
NYC	New York	
CCS	Caracas		–04.0	La Paz, Santiago, Port Of Spain
YHZ	Halifax		
YYT	St. Johns	–03.5	
RIO	Rio De Janeiro	–03.0	Sao Paulo, Buenos Aires, Brasilia, Montevideo
RAI	Praia		–01.0	
LIS	Lisbon		+00.0	Dublin, Casablanca, Dakar, Abidjan
LON	London		
BCN	Barcelona	+01.0	Amsterdam, Algiers, Hamburg, Frankfurt, Vienna
MAD	Madrid		
PAR	Paris		
MIL	Milan		
ROM	Rome		
BER	Berlin		
STO	Stockholm	
ATH	Athens		+02.0	Helsinki, Istanbul, Beirut, Damascus,
CAI	Cairo		        Cape Town
JRS	Jerusalem	
MOW	Moscow		+03.0	Kuwait, Riyadh, Aden, Addis Ababa, Nairobi
JED	Jeddah		
THR	Tehran		+03.5	Shiraz
DXB	Dubai		+04.0	Abu Dhabi, Muscat
KBL	Kabul		+04.5	
KHI	Karachi		+05.0	Male
DEL	Delhi		+05.5	Mumbai, Kolkata
DAC	Dhaka		+06.0	Colombo
RGN	Yangon		+06.5	
BKK	Bangkok		+07.0	Jakarta, Phnom Penh, Hanoi, Vientiane
HKG	Hong Kong	+08.0	Singapore, Kuala Lumpur, Beijing, Taipei,
				Manila, Perth, Ulaanbaatar
SEL	Seoul		+09.0	Pyongyang
TYO	Tokyo		
ADL	Adelaide	+09.5	Darwin
GUM	Guam		+10.0	Melbourne, Rabaul
SYD	Sydney		
NOU	Noumea		+11.0	Port Vila
WLG	Wellington	+12.0	Christchurch, Nadi, Nauru Island

possibly squoze to Radix 50/Mod 40 (recently revived) or 5 bit Baudot code:



Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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