Oct. 21, 2018
11:50 p.m.
Michael H Deckers via tz wrote:
time-of-day values on or after 24 hours may be ambiguous due to leap seconds.
Only if we decide they're ambiguous. Instead, let's resolve the ambiguity in the obvious and useful way.
The fictitious UTC time stamp "2016-12-31T25Z" could indeed be taken to mean 2016-12-31T00Z + 25 h = 2017-01-01T00:59:59Z or else 2017-01-01T00Z + 01 h = 2017-01-01T00:00:00Z.
Only the latter meaning is useful in tzdb, so let's do it that way. We went through this issue a while ago with "rolling" versus "stationary" leap seconds, only one of which is useful in practice, and in hindsight we should have supported only the useful variant.