TZ Changing in Chile on May, 14th.
Dear IANA TZ, Since the last time change Chile has been in GMT-3 (i.e. Chile is right now in GMT-3). Chile is going to GMT-4 in May,14th midnight and returning to GMT-3 in August, 13th midnight. That means clocks will go back 1 hour at 00:00 May 15th (jumping back to May 14th); and will go forward by 1 hour on 00:00, August 14th. In tzdata2016c I can see this new rules for Chile: # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S Rule Chile 2016 max - May Sun>=9 3:00u 0 - Rule Chile 2016 max - Aug Sun>=9 4:00u 1:00 S And I can see this Chile zone definition: # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone America/Santiago -4:42:46 - LMT 1890 -4:42:46 - SMT 1910 Jan 10 # Santiago Mean Time -5:00 - CLT 1916 Jul 1 # Chile Time -4:42:46 - SMT 1918 Sep 10 -4:00 - CLT 1919 Jul 1 -4:42:46 - SMT 1927 Sep 1 -5:00 Chile CL%sT 1932 Sep 1 -4:00 - CLT 1942 Jun 1 -5:00 - CLT 1942 Aug 1 -4:00 - CLT 1946 Jul 15 -4:00 1:00 CLST 1946 Sep 1 # central Chile -4:00 - CLT 1947 Apr 1 -5:00 - CLT 1947 May 21 23:00 -4:00 Chile CL%sT But with these two information I'm not sure that in the midnight of May, 14th this tzdata2016c will change the TZ of Chile from GMT-3 to GMT-4. Can you please explain me how these structures in tzdata2016c work to accomplish the necessary TZ change in Chile. Thank you very much, best regards. Luis
On 05/02/2016 04:08 PM, Luis Martinez Villa wrote:
Can you please explain me how these structures in tzdata2016c work to accomplish the necessary TZ change in Chile.
Before the transition, this rule line is active: Rule Chile 2012 2014 - Sep Sun>=2 4:00u 1:00 S so Chile is assumed to be on daylight saving time, i.e., -03. You can verify this by running 'zdump -c2016,2017 -v America/Santiago'. Its output should contain: America/Santiago Sun May 15 02:59:59 2016 UT = Sat May 14 23:59:59 2016 CLST isdst=1 gmtoff=-10800 America/Santiago Sun May 15 03:00:00 2016 UT = Sat May 14 23:00:00 2016 CLT isdst=0 gmtoff=-14400
Before the transition, this rule line is active:
Rule Chile 2012 2014 - Sep Sun>=2 4:00u 1:00 S so Chile is assumed to be on daylight saving time, i.e., -03.
I catch myself making the same mistake sometime. It's easy to think that since the "TO" column is 2014, that there was no savings in effect in 2015. However, it actually just means that there was no *transition* in 2015. So the last transition to occur left the 1 hour savings in effect (UTC-03:00), which persists until it is removed by the next transition in May of 2016. -Matt
participants (3)
-
Luis Martinez Villa -
Matt Johnson -
Paul Eggert