[tz] EST/EDT vs AEST/AEDT in AQ

[Tobias Conradi]

On Mon, Apr 15, 2013 at 6:57 PM, Paul Eggert <eggert at cs.ucla.edu> wrote:
> On 04/15/13 07:59, Tobias Conradi wrote:
>
>> Reserving D in %s for 1:00 offset as has been done over years, i.e. is
>> established practice
>
> I'm not quite following all the proposal in this area, but "D"
> also stands for "Double", as in BDST for British Double Summer Time.
> There is a similar usage of "H" for Half, as in CKHST for
> Cook Islands Half Summer Time.  If memory serves, CKHST, UYHST, etc.
> are my own invention, while BDST is not: it comes from contemporaneous
> British sources.  I came up with HST by analogy from DST.

My statement was a shortening, that shortening made it wrong.

I meant in the position immediately before the last T.

For saving time there is immediately before the last T
D 1:00
S 1:00
DD 2:00
DS 2:00
HD 0:30
HS 0:30 and 0:20

Conforming with this established practice is LHHDT for Lord Howe Half
Daylight saving Time.

In the beginning of the 1980 saving was 1:00, so I proposed LHDT
there. In 1985 there was both.

Until March 1:00 saving, suggesting LHDT. From October 0:30 saving,
suggesting LHHDT.

If in October the abbreviation is the same, then it might be
confusing. It could be that the data source for a clock was not
updated, and it uses 1:00 by error. If one clearly distinguishes
between half and full hour saving in the abbreviation, then everyone
who sees a clock time and the abbreviation, is at least pointed to the
fact that something is not as in the saving periods before.

An area can also split during saving time, and xDT and xHDT exist side
by side. If one would label both as xDT, there could be the same
tsunami warning ambiguities as mentioned by the Australian BOM people
to this mailing list.

Summary for Lord Howe:

LHST Lord Howe Standard Time - save 0:00
LHDT Lord Howe Daylight saving Time - save 1:00
LHHDT Lord Howe Half Daylight saving Time - save 0:30

--
Tobias Conradi
Rheinsberger Str. 18
10115 Berlin
Germany

http://tobiasconradi.com