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 ([email protected])
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