[tz] Java & Rearguard

Stephen Colebourne scolebourne at joda.org
Fri May 31 15:31:49 UTC 2019

Unfortunately I don't run on Linux, so can't check this. I've tried
looking for the relevant source code in OpenJDK, but haven't seen
anything obvious that might parse this format. This was the closest I


On Fri, 31 May 2019 at 03:08, Paul Eggert <eggert at cs.ucla.edu> wrote:
> On 5/30/19 2:14 AM, Stephen Colebourne wrote:
> > It is a compatibility requirement of the main Java libraries
> > (including icu4j IIUC) that DST is always positive.
> Where is this documented? And what do the main Java libraries do in an
> environment where the DST offset is negative? For example, if I run the
> following shell command on a POSIX-compatible host:
> TZ='IST-1GMT0,M10.5.0,M3.5.0/1' java [arguments]
> can you give an example of what goes wrong and why? This command gives
> Java the rules that Ireland has used since 1996, with Irish Standard
> Time (1 hour ahead of GMT) used in the summer and GMT (a "negative
> daylight saving time") in the winter.

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