On 12/05/2018 06:02, Lester Caine wrote: > > In part I can accept that, but short cuts need to be documented? It is > not common knowledge that TZ data IS questionable prior to 1970, and > with the amount of research being done on even just the second world > war, knowing that time one is normalizing needs knowledge of the > situation at that time. My digging into the German occupation of the > Channel Islands threw up the errors there with local time being adrift > from the rest of the UK! > > Dropping seconds accuracy and merging timezone into the same restricted > data field is a shortcut that has major limitations. First, prior to > standardised time we assume mid-day happened when the sun was directly > over head, so the rule for the whole world was LMT. Using Greenwich as a > timing point may only date back to 1675 and was only officially adopted > in 1880 but it is the current base. America joining in 3 years later and > the basis for timezones was established in 1884. So any date prior to > 1884 do not have timezones and are identified by their LMT offset. While > time prior to the introduction of accurate measuring devices may be > somewhat academic and millisecond accuracy totally pointless, that early > 19th century time had well documented differences of seconds. So any NEW > facility should at least permit those variations to be handled. Or > simply say 'the Firebird TIMEZONE extension is only accurate for dates > post 1970'. > > In my book a normalized time consists of FOUR elements. UTC based time, > offset, rule set, version. I don't think any of the current 'solutions' > offered by any database respects this and so even for CURRENT diary > events they have no way of flagging when the calculated offset has been > compromised. TZdist was an attempt to plug these holes, but has yet to > even start being used despite the fact that it is the perfect solution > for time management on 'internet devices'. I have also been advised of a > new ietf task group to address the Geolocate Extension and the Time Zone > Information Format bu these will be some time reaching an RFC stage :( >
The discussion is going to a place that the next part will be about time zones as we know not works outside of Earth. Adriano ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
