On 5 June 2016 at 19:51, Paul Eggert <eggert@cs.ucla.edu> wrote:
> choosing the local time *after* the transition isn't how most people think
> about transitions in day to day conversation.

 True. But it's easy to get used to when looking at zdump -i format. Plus, users most likely prefer localtime to UT when thinking about transitions.

I realize the goal may be to have a single canonical format, but perhaps this could be made conditional on a -z option?  Append a "Z" to the time-of-day when it's UT; don't when it's local.  One of the good things the existing -v format provides is the ability to confirm that transitions occur at both the correct local time and Universal time.

To some extent there is a tradeoff between formats that make typos easy to find, and formats that are more what users typically expect. Within reason I'd rather make typos easy to find

Just to throw in a potential middle-of-the-road option, would it make sense to space-pad the datetime and offset values instead?  Something like the following:

TZ="America/Phoenix"
-          -        -072818 LMT
1883-11-18 12       -07     MST
1918-03-31 03       -06     MDT 1
1918-10-27 01       -07     MST
1919-03-30 03       -06     MDT 1
1919-10-26 01       -07     MST
1942-02-09 03       -06     MWT 1
1943-12-31 23:01    -07     MST
1944-04-01 01:01    -06     MWT 1
1944-09-30 23:01    -07     MST
1967-04-30 03       -06     MDT 1
1967-10-29 01       -07     MST

TZ="Pacific/Pago_Pago"
-          -        +123712 LMT
1879-07-04 00       -112248 LMT
1911-01-01 00:22:48 -11     NST
1967-04-01 00       -11     BST
1983-11-30 00       -11     SST

I think that strikes a balance where typos are easy to spot, but the purpose of each field remains quite reasonably clear.  The handful of extra bytes seem a worthwhile expense to have a canonical format which can easily serve both humans and machines alike.

(I would not, however, suggest padding the later fields.)

typos are a real probelm!

;)

--
Tim Parenti