[tz] Fiji DST for 2012-2013 announced

Ian Abbott abbotti at mev.co.uk
Fri Sep 7 11:16:19 UTC 2012

On 2012-09-05 21:19, random832 at fastmail.us wrote:
> (oops, sent it directly instead of to the list at first)
> On Sun, Sep 2, 2012, at 00:12, lord.buddha at gmail.com wrote:
>> I now also wonder if the
>> presumption of a pattern might cause conflicts with other sources.
>> IATA / Microsoft etc.
> I think Microsoft's practice has generally been to have extrapolated
> rules, hope for the best, and publish a hotfix if it doesn't match. My
> (unpatched) Windows 7 machine extends the 2010 rule [Fourth Sunday
> October to Last Sunday March] on to infinity.

On my up-to-date Windows 7 system, the recurring rule for Fiji runs from 
the Fourth Sunday of October to the Fourth Sunday of January:


(see <http://msdn.microsoft.com/en-us/library/ms725481.aspx> for 

It currently has dynamic DST rules for years 2008 to 2013, but the 
information for the 2012-2013 DST period is currently incorrect.  They 
have DST beginning on the 4th Sunday of October 2012 (2012-10-28) and 
finishing on the 1st Sunday of March 2013 (2013-03-03):


Presumably they'll get round to fixing it on their next round of time 
zone updates.

> They have published at
> least two updates since then that I've been able to find that tweak the
> rules, and I haven't verified firsthand but have no particular reason to
> doubt they similarly extend the then-latest rules [Fourth Sunday January
> to First Sunday March, based on update description text] indefinitely,
> and expect to publish further hotfixes.

Microsoft's time zone information cannot encode penultimate Sundays, so 
if that's the rule, they'll have to use a "dynamic" DST rule each year, 
or change the way they store and interpret time zone information (which 
would have knock-on effects for applications that store and retrieve 
time zone information).


They don't store much historic information and only allow two 
transitions per year, so the temporary suspensions of DST by various 
also throw a spanner in the works, requiring hot-fixes to be applied at 
certain times of the year in those countries.

-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti at mev.co.uk>        )=-
-=( Tel: +44 (0)161 477 1898   FAX: +44 (0)161 718 3587         )=-

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