Re: [tz] Was there a 1971-12-31 23:59:60?

Paul Gilmartin via tz wrote:

"leap-seconds.list" shows one more leap second that "leapseconds".

No, because the file "leap-seconds.list" is not merely a list of leap seconds; it is a list of corrections to apply to TAI to get modern UTC, which is a somewhat different thing. That file's first entry is the first such correction to apply, and this correction is not a leap second. I installed the attached patch into the tzdb development version to try to clarify this in the tzdb "leapseconds" file, without going into too much detail.