[LEAPSECS] Common Calendar Time (CCT) -Brooks Harris
    Brooks Harris 
    brooks at edlmax.com
       
    Sun Jan 19 00:45:04 EST 2014
    
    
  
On 2014-01-18 09:29 PM, Tom Van Baak wrote:
> Brooks,
>
> Maybe I missed it way back in the thread, but can you give me an example why you'd want a proleptic TAI or UTC?
I'm working on revising the names and a fuller explanation, but briefly -
The idea is to declare a 1hz timeline before 1972-01-01T00:00:00Z (UTC) 
= 1972-01-01 00:00:10 (TAI). I'd called these "proleptic UTC" and 
"proleptic TAI", but I agree, that's a bad way to explain it.
The purpose is to provide a scale so the exact offsets to some other 
important timescales, such as NTP, POSIX, and 1588/PTP can be explicitly 
declared. This is a contrivence for computational convenience.
I'm working on a revision of this table, which I posted earlier, but 
perhaps this gives an idea what I'm trying to accomplish  -
-----------------------------------------------------------------------------------------
Origin      |  UTC1972    | Coincides   |          UTC |Leap|        TAI
Name        |  Seconds    | with        | |Secs|
             |  Offset     | Origin of   |                   ( Earth  )
             |             |             | (Correction)
             |             |             | |    | 
-----------------------------------------------------------------------------------------
UTC1900     | -2272060800 | NTP         | 1900-01-01T00:00:00Z | 10 | 
1900-01-01 00:00:10
TAI1958     |  -441763210 | TAI         | 1957-12-31T23:59:50Z | 10 | 
1958-01-01 00:00:00
TAI1970     |   -63072010 | 1588/PTP    | 1969-12-31T23:59:50Z | 10 | 
1970-01-01 00:00:00
UTC1970     |   -63072000 | POSIX       | 1970-01-01T00:00:00Z | 10 | 
1970-01-01 00:00:10
TAI1972     |         -10 | UTC + 10s   | 1971-12-31T23:59:50Z | 10 | 
1972-01-01 00:00:00
UTC1972     |           0 | UTC         | 1972-01-01T00:00:00Z | 10 | 
1972-01-01 00:00:10
UTC1972_7_1 |   +15724800 | First Leap  | 1972-07-01T00:00:00Z | 11 | 
1972-07-01 00:00:11
UTC1980_1_6 |  +252892800 | GPS Epoch   | 1980-01-06T00:00:00Z | 19 | 
1980-01-06 00:00:19
-Brooks
>
> /tvb
>
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