[tz] isdst bug Europe/Dublin (tzdb-2019c)

Clive D.W. Feather clive at davros.org
Fri Dec 13 22:13:36 UTC 2019

Stefan Rueger said:
> I feel there were missed opportunities, too, when developing standards: Rather than foregrounding time difference to GMT and isdst (1 for DXT "daylight changed time", 0 for normal and -1 for unknown) one might have foregrounded the difference to what the region considers its normal time zone and the current offset owing to DXT, if any. Using the current interpretation the DXT offset would be -1 for Ireland and 1 for the UK (while Antarctica/Troll would be 2 and Lord Howe Island 0.5). That way the difference to GMT would be the sum of slow changing (geographic timezone) and potentially annually changing (DXT) offsets. In my mind this would have been more informative and easier to understand than isdst.

I don't disagree with you. The problem is that the original standards were
mostly written by US people who assume that the whole world works their way.
Where there's a clean sheet to start from, we can do better things [1], but
that's a lot harder with a large installed base.

The US-centric problem isn't new to this. I've lost count how many web
sites can't cope with the fact that I don't have a zip code or that I have
two middle initials, not one. I'm lucky that I don't have any non-ASCII
characters in my name; there's a whole nother minefield waiting there.

Allow me to point you at:

[1] For example, I've ensured that the Bluetooth Mesh standard uses TAI
internally for all timestamps, leaving the leap second mess to the

Clive D.W. Feather          | If you lie to the compiler,
Email: clive at davros.org     | it will get its revenge.
Web: http://www.davros.org  |   - Henry Spencer
Mobile: +44 7973 377646

More information about the tz mailing list