12.05.2018 1:12, Lester Caine wrote:
On 11/05/18 20:37, Adriano dos Santos Fernandes wrote:
* PST is Pitcairn or Pacific, with the same offset, they are
considered different time zones
ICU data is derived from TZ data hosted by IANA
(http://site.icu-project.org/tznotice).
I really can't answer questions about specific time zones, but really
grateful if we can clarify them.
The abbreviations are not defined to be unique. Only a subset of them can be used as identifiers, the rest are only 'defined' when
associated with a particular rule, so are only suitable for displaying.
Personally I need to see the different UK/Ireland timezone idents giving the right offsets prior to 1970 and that depends on how the
ICU extract has been processed. It's not a case that 'the ICU data is derived from TZ data', it also depends on how the TZ data is
processed by ICU and I'm not seeing ANY information on that. For the Irish area we then get IST standing for Irish Summer Time prior
to 1968, and Irish Standard Time after that. Nothing is easy on any of this ... and IST is used in a number of other rules with
similar differences in expansion. A quick scan of the ICU files would suggest 'IST' is used by them for India Standard Time but it
would be nice if there was an easy way to confirm that? Certainly I'm not seeing data in zoneinfo64.txt for Isle of man, Jersey,
Guernsey or Belfast so I suspect they are not valid pre-1970 :(
Probably, this answers on (some of) your questions
http://userguide.icu-project.org/datetime
http://userguide.icu-project.org/datetime/calendar
http://userguide.icu-project.org/datetime/timezone
Regards,
Vlad
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