Guy Harris wrote:
https://bugs.java.com/bugdatabase/view_bug.do?bug_id=4263805
Presumably meaning "in theory, Java could be run, on a system that supports the full POSIX syntax for TZ, with TZ set to arbitrary POSIX-compliant values, including values in which clocks are turned *backwards* from standard time in the autumn and winter, but, in practice, that's insufficiently likely that there's any reason to make Java support it".
Yes, it seems that this was reported as a Java bug 20 years ago and ignored on the ground that tzdb TZ settings were so much better that there was no need to support POSIX TZ settings. Unfortunately, as we've discovered since then, Java doesn't fully support tzdb TZ settings either. It is odd to see the 2016-09-26 comment "Not a popular request" in a bug report that has with so many duplicates. Perhaps that was snark?
Paul, how should we go about requesting an interpretation from TOG here?
I could do that, but I don't see what sort of interpretation is needed. POSIX clearly requires support for a TZ setting like 'IST-1GMT0,M10.5.0,M3.5.0/1' that specifies negative DST, and that is true regardless of what Ireland happens to be doing right now.