[tz] inventing zone abbreviations
lester at lsces.co.uk
Tue Feb 16 12:20:40 UTC 2016
On 16/02/16 11:56, Barbara Canino wrote:
> In addition to that, I would like to point out that introducing strings like "+04", "+0400", "UTC+04", "UTC+0400" instead of abbreviations is providing information that is already available: programs can easily calculate and display any of the strings above using the GMT offsets available in tz files.
BUT you need to know the location as part of the time to do that ...
If you send me 12:00 UTC+04 then I know both current local time and UTC
time, but I don't know the local time offset 6 months from now.
My problem and the reason I started taking an interest in tz is that
data which has been normalised to UTC in the past is now useless because
we have no reference to just what rules were used. Even today there is
no easy way of establish if a diary normalised to UTC is using DST rules
that have changed recently. Having a unique abbreviation is not the
solution either, but may at least flag the potential problem.
Moving forward, being able to identify both the rule used and the
version of that rule is essential for SOME areas of calendering. One can
get away with short cuts some of the time, but once the data becomes
archived, being able to work with it later may be a problem if the
version of tz (warts and all) is not identifiable.
Lester Caine - G8HFL
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