Re: [LEAPSECS] building consensus

From: Zefram <>
Date: Tue, 6 Jun 2006 00:00:20 +0100

Rob Seaman wrote:
>One might ponder what standards body is responsible for the
>international calendar specification. Is it the Roman Catholic

The RCC is authoritative for no calendar other than the RCC calendar.
Originally this amounted to an endorsement of the Roman empire's
then-current civil calendar, namely the Julian calendar, plus a
formula for the date of Easter. The RCC then commissioned, and
eventually endorsed, the replacement Gregorian calendar, along with
a new Easter formula. Any future changes to the RCC calendar make no
difference whatsoever to the use of the Gregorian calendar by any other

> Or has the specification passed into the public domain?

The algorithm is well-known and immutable. It is independent of any
authority. One might equally refer to it as the "ISO 8601 calendar"
rather than the "Gregorian calendar".

> Are
>individual nations each responsible for their own calendars?

Trivially yes, as a matter of law. It is precisely the same issue as
time zones.

>mustn't they then be responsible for trade and scientific purposes
>for providing tables of conversions between their national calendar
>and the international standard? Which then returns us to the
>question of who is responsible for that international standard...

Anyone promulgating a calendar is de facto responsible for providing
the mapping between day labels and actual days. There's no de jure
compulsion, but if they don't do this then it's no use as a calendar.
Converting to other calendars is (conceptually) the composition of more
than one of these mappings. The international standard, in this sense,
is actual planetary rotations.

Or you could view some form of Julian Date as the international standard.
The Chronological Julian Day Number has some currency as a calendar
intermediate format. This too doesn't need any responsible authority:
the definition is well known.

>A calendar counts days. A day - whether from noon to noon, midnight
>to midnight, sunrise to sunrise, or sunset to sunset - is an atomic
>"quanta" of time on earth.

I think this is no different from the situation with leap seconds.
The precision time services, in TAI and UTC, provide a standardised
1 Hz cycle, dividing up proper time on the geoid into quanta of (as
close as can be realised) 1 s. A leap second encompasses exactly one of
these quanta. The difference between days of the Gregorian calendar and
seconds of UTC is merely that the seconds are an artificial phenomenon.

Received on Mon Jun 05 2006 - 16:00:57 PDT

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