On 2014-01-17 04:06 AM, Zefram wrote:
C) By declaring the anchor-point to existing TAI and UTC definitions
as 1972-01-01T00:00:00Z we have imposed an *uncompensated* Gregorian
calendar counting scheme on the proleptic part of the new timescale,
making 0000-01-01T00:00:00Z the origin of the new timescale.
The proleptic Gregorian calendar is not limited in year range.
Negative CE year numbers are valid, commonly used in astronomy, and ISO
8601 provides syntax for them. 0000-01-01 was preceded by -0001-12-31.
There's no real origin here; the closest thing is the synchronisation
point nominated by ISO 8601 at 1875-05-20 (the signing of the Convention
of the Metre).
Yes, I understand that. Perhaps using the word "origin" was careless.
Maybe you can suggest a better term.
The point was to make it clear there is a "0000-01-01T00:00:00Z" "date"
on the new timescale, that dates earlier are negative, as you indicate,
and dates later are positive.
Of course the idea is that dates after 1972-01-01T00:00:00Z are "earth
corrected" (Leap Seconds). Application of "earth corrections" prior to
1972 as they are applied to the NTP "prime epoch" for example, will need
careful explanation.
-Brooks
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