On Feb 22, 2:23 pm, markjr...@gmail.com ("Mark J. Reed") wrote:
> I submit that if the inputs and outputs of Temporal are UTC, then Perl
> is using UTC, not TAI.  Is it TAI internally?

Only the time scale which is approved by the ITU-R for use in radio
broadcasts has any international backing.  Because it is the
internationally-approved and broadcast time scale there are many
systems which rely on its value, and for that reason it is the only
practical choice for many applications and specifications.  At present
that time scale is called UTC, and at present it has leap seconds.  If
those are not suitable for an application then there is little option
but to create one's own time scale with the necessary
characteristics.  POSIX has created its own time scale, but confusion
and problems result from calling it UTC.

It is probably worth pointing out that TAI is maintained only by the
BIPM, and if asked the BIPM will almost certainly respond that it is
not appropriate to use TAI for any standard purposes.  Past objections
from various folks have included metrological jargon such as TAI is
"not realized" or "not available"; that only UTC is "realized".  The
same folks have objected to the use of GPS time because it is a US
Department of Defense time scale with no international authority
behind it.

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