[tz] Norfolk Island, Daylight Saving Time (DST) 6/10/19-05/04/20 [SEC=UNCLASSIFIED]

[Kyle Czech]

Hi all,

Please see further clarification below from our legislation and policy team.

The references to ‘2am’ in the definition of ‘daylight saving period’ in s 4 of the Norfolk Island Standard Time Ordinance 2015 should be read as references to ‘standard time’. That is, the ‘daylight saving period’  begins at 2am (‘standard time’) on the first Sunday in October, when clocks are put forward one hour. It ends at 2am ‘standard time’ (which is 3am ‘daylight saving time’) on the first Sunday in April, when clocks are put back one hour. The relevant provisions in the Norfolk Island Standard Time Ordinance 2015 are based on the equivalent legislative provisions in the other Australian jurisdictions where daylight saving is observed.

Accordingly, these arrangements regarding the commencement and ending of the ‘daylight saving period’ are consistent with the other Australian jurisdictions where daylight saving is observed. 

See https://www.australia.gov.au/about-australia/facts-and-figures/time-zones-and-daylight-saving

Regards,
Kyle

Kyle Czech
Community, Local Government and Assets
Norfolk Island and Mainland Territories Branch, Territories Division 
Department of Infrastructure, Transport, Cities and Regional Development 
t 0011 6723 23315 (DITCRD)
t 0011 6723 22152 (OoA)
m 0011 6723 53523
w www.infrastructure.gov.au

-----Original Message-----
From: Paul Eggert [mailto:eggert at cs.ucla.edu] 
Sent: Thursday, 15 August 2019 11:27 AM
To: Brian.Inglis at SystematicSw.ab.ca
Cc: Time zone mailing list <tz at iana.org>; Kyle Czech <Kyle.Czech at infrastructure.gov.au>
Subject: Re: [tz] Norfolk Island, Daylight Saving Time (DST) 6/10/19-05/04/20 [SEC=UNCLASSIFIED]

Brian Inglis wrote:
> As thin as in an Australian winter: that page is not "normative" 
> legislation, which by default refers to the local legal time in effect 
> in the reference, as stated in 8(1) and 8(2)

Unfortunately the Norfolk Island legislation is ambiguous. By stating that DST ends at 2 o'clock, it allows either a 02:00->01:00 transition (which occurs at 2 o'clock local time, valid legal daylight saving time at the instant of transition), or a 03:00->02:00 transition (which also occurs at 2 o'clock local time, valid legal standard time at the instant of transition).

This ambiguity is inherent to timestamps near a fallback transition. It's not an ambiguity that can occur with tzdb timestamps, since our digital clocks would tick from 01:59.999999999 to 01:00 (or from 02:59.999999999 to 02:00) during a fallback transition. However, it can occur in the continuous-time model that legislation invariably uses.

Possibly the Norfolk Island legislation copied boilerplate from other Australian law, in which case the legal wording is ambiguous elsewhere in Australia. It would be helpful if the Australians would add a phrase or two to disambiguate this, the next time they change their DST laws.


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