On Mon, 3 Mar 2025 at 16:01, Doug Ewell via tz <tz@iana.org> wrote:

2. Is there an easy way I could have looked up this information in the tz files?

(“Easy” means without exhaustively parsing all the Rule and Zone lines, as a processor would have to do.)

Not sure if you count grep as a processor, but you can drill down crudely with:

grep -n "^Rule.*max" africa antarctica asia australasia europe northamerica southamerica

Currently this yields the 52 lines which define Rules that continue until the max year. This is not strictly the same as "current practice", but rather "latest-dated ongoing prediction". (It also doesn't guarantee the Rules are actually used anywhere.)

A quick visual scan of the penultimate column shows that all such SAVE values have an absolute value of either 0 or 1:00, apart from the Troll and LH rules as have been mentioned by others as the only exceptions.

--
Tim Parenti