Alfie John <alfie@fastmail.com> writes:

Hi TZers,

Sorry if this has been asked before, but I couldn't find any documentation on the rules of what should happen for the following circumstances.

Here's the definition for Australia/Brisbane:

# Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S Rule AQ 1971 only - Oct lastSun 2:00s 1:00 D Rule AQ 1972 only - Feb lastSun 2:00s 0 S Rule AQ 1989 1991 - Oct lastSun 2:00s 1:00 D Rule AQ 1990 1992 - Mar Sun>=1 2:00s 0 S Rule Holiday 1992 1993 - Oct lastSun 2:00s 1:00 D Rule Holiday 1993 1994 - Mar Sun>=1 2:00s 0 S Zone Australia/Brisbane 10:12:08 - LMT 1895 10:00 Aus AE%sT 1971 10:00 AQ AE%sT

As the zone ends with AQ, and AQ does not have a "max" ending date, what should Australia/Brisbane fall back to after 1992?

Er, there is a spring forward rule in 1993, and a fall back rule in 1994, and it ends on standard time.

Date: Wed, 04 Nov 2015 10:18:44 +1000 From: Alfie John <alfie@fastmail.com> Message-ID: <1446596324.2469321.428397441.42FF90BD@webmail.messagingengine.com> | As the zone ends with AQ, and AQ does not have a "max" ending date, what | should Australia/Brisbane fall back to after 1992? Nothing, it remains on AQ forever. It is just that AQ has no more transitions after 1992, so the time just remains stable (Queensland has no summer time variation normally.) | I thought maybe in | this instance perhaps "Aus" as it's the one above it, but "Aus" seem to | oddly be specific to both World Wars. In Australia, time is controlled by the states, usually (war time can be different...) hence different rules for the different states. AQ represents Australia Queensland. kre

Alfie John <alfie@fastmail.com> writes:

If you're referring to "Holiday", I don't see how that applies to "Australia/Brisbane" seeing as there it's not included in its zone rules.

Sorry, didn't look closely, assuemd it was relevant because you pasted it. But the same thing applies, for real, for the rules for 1991 and 1992. Spring forward Oct 1991, fall back Mar 1992.

On 3 November 2015 at 20:57, Alfie John <alfie@fastmail.com> wrote:

So as Australia/Brisbane is still on AQ as you say, and AQ no longer has any rules active, I should go with GMTOFF = 10:00, meaning that Brisbane is currently equivalent as GMT+10 (i.e. has no DST).

Yep; that's how you interpret that line. -- Tim Parenti

On Wed, 4 Nov 2015, Alfie John wrote:

On Wed, Nov 4, 2015, at 11:33 AM, Robert Elz wrote:

...

Oh, I forgot to say in the last reply, that you (always) work out which rules apply from the Zone line, never from what is in the rules themselves.

Yep, that's what I was assuming.

...

For Australia/Brisbane we have (as you indicated...)

Zone Australia/Brisbane 10:12:08 - LMT 1895 10:00 Aus AE%sT 1971 10:00 AQ AE%sT

The last of those lines has no "UNTIL" value, hence does not end (which is normal for a zone specification, time is not expected to end anywhere I know of, or not anytime within the range of tzdata.)

Awesome, thanks for that. So as Australia/Brisbane is still on AQ as you say, and AQ no longer has any rules active, I should go with GMTOFF = 10:00, meaning that Brisbane is currently equivalent as GMT+10 (i.e. has no DST).

It's not a question of "any rules active." Rather it's a question of whether there are additional transitions defined. There are none, so Australia/Brisbane stays on its current time indefinitely. +------------------+--------------------------+-------------------------+ | Paul Goyette | PGP Key fingerprint: | E-mail addresses: | | (Retired) | FA29 0E3B 35AF E8AE 6651 | paul at whooppee.com | | Kernel Developer | 0786 F758 55DE 53BA 7731 | pgoyette at netbsd.org | +------------------+--------------------------+-------------------------+