Poul-Henning Kamp wrote:
In message <[EMAIL PROTECTED]>, Rob Seaman writes:
Jim Palfreyman wrote:

Just a reminder that UTC has no - none - nada - discontinuities.
Various computer mis-implementations may, but the standard is very
carefully constructed to avoid spring-forward or fall-back gaps or do-

Rob, If you feel uncomfortable with calling leapseconds
discontinuities, then we can use the term arrhythmia instead.

If we assume that every month has 30 days and obtain a day
number by multiplying the month number by 30 and adding
the day in month (call this the SDN - Silly Day Number) and
then look at SDN-MJD (modified Julian day number) we would
see discontinuities.

The only way to see discontinuities in UTC-TAI is by making
an equally silly assumption in numbering the seconds of
UTC: assuming all UTC minutes are 60 seconds or, equivalently,
all UTC days are 86 400 seconds.

The unfortunate thing is that people actually do think of it
this way.  E.g.:


The whole idea of the expression UTC-TAI being meaningful
and evaluating to a number of seconds is a convenient but
rather sloppy shorthand.  Any strongly typed programming
language ought to give a type error on that expression.

UTC times of day are variable radix - in just the same way
as days and months are in the Gregorian calendar.

Except, of course, that the Gregorian calendar is fixed and
completely predicable.  I have an awful lot of sympathy for
the idea of making leap seconds predictable over longer
periods, even if it risks UTC-UT1 becoming larger than at
present allowed.


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