[LEAPSECS] Leap Seconds schedule prior to 1972

[Brooks Harris]

Hi John,

I like the idea in general, even if its a solution in search of a 
problem. I think many fields would find it useful if it found agreement 
and acceptance.

Consider this:

For your "specification" I'd suggest you define the data type 
generically so it can be implemented, represented, and transported by 
various platforms and technologies - c/c++, Java, .NET, XML, REST, SQL, 
etc, etc.

There are two critical data values: the "date" value and the TAI-UTC 
value. Some *comments* in YMDhms form is probably be helpful (what does 
date -123456 mean?), but the "date" variable value takes precedence.

Define day zero as the first day of the integral UTC era - 1972-01-01 
00:00:10 (TAI) = 1972-01-01T00:00:00 (UTC) is the calibration point at 
which the relationship between atomic time and observed mean solar time 
was made to converge on exactly 10 integral seconds as determined by the 
development process of UTC.

Use negative 86400 second days as the "date" variable. Thus the last day 
of your timescale is -1, which is also the last day of the "rubber band 
UTC era" .

With that you've created a timescale of your own with no confusion or 
controversy with Julian date, MJD, or NTP seconds and with an 
unambiguous relation to UTC. A statement of how each of these are 
aligned to your proleptic timescale might be useful or necessary but 
your timescale is not dependent on the definitions or interpretation of 
these other timescales.

The range is as high as you want - its probably not necessary to point 
out a signed 64-bit day number value is a very large number of days, 
something like -25,252,216,391,115,000 years, which should cover it. 
I'll leave it to your research to decide how many Leap Seconds that 
might require.  :-)

I'd also point out a data type using a 21-bit day number counter and an 
11-bit TAI-UTC value variable can support a range of approximately 3000 
years in 4 bytes, 32-bits. This is a nice small data type suitable for 
fast transfer and compact storage in binary implementations.

-Brooks

On 2016-04-23 03:52 PM, John Sauter wrote:
> On Sat, 2016-04-23 at 02:34 -0700, Hal Murray wrote:
>>   
>> Keyword-value is good.
>>
>> You may want to allow comments on the end of content lines.
>>
>> The julian-day and year-month-day look redundant.  I wouldn't do
>> that.  It
>> leads down the rathole of what to do if they don't agree.
>>
>> Don't over engineer it.  Write some sample code.
>>
>>
> Challenge accepted!  I should have some code to post, along with a
> sample data file, in a few days.
>      John Sauter (John_Sauter at systemeyescomputerstore.com)
>
>
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