[tz] JavaScript IANA date/time library, now with support for leap seconds, TAI, TDT

[Paul Gilmartin]

On 2021-04-26, at 13:15:22, Kerry Shetline via tz wrote:
>    ...
>> * There is a fixed, defined relationship between POSIX time and future
>>   calendar dates and times, but that isn't true for TAI.
> 
> POSIX time is really just UTC without the leap seconds, isn’t it?
> 
More precisely, POSIX time counts non-leap seconds since 1972-01-01t00:00:00 UTC.

Is there a problem other than ambiguity:
that 2016-12-31t23:59:60 UTC
and 2017-01-01t00:00:00 UTC are represented
by the same POSIX time?

Doesn't TAI use the Gregorian calendar, so 
2017:01:01t00:00:00 TAI is
2016:12:31t23:59:23 UTC.  That's just a timezone convention
-- the date may differ among various timezones.

-- gil