Re: A few questions

[brbarkstrom@gmail.com]

You could translate the YYYYMMDD time into a continuous numerical value
and then use Ada.Real_Time to convert that value to time in seconds from
some selected starting point.

The way astronomers track time is to go over to counting seconds from 
Jan. 0, 2013 BCE.  The variable is called Astronomical Julian Date.
The current value is fairly large, particularly if you want a time 
resolution in microseconds.  GPS time is close to Julian Date, but
uses a starting date closer to the present.

Seidelmann, P. K., 2006: Explanatory Supplement to the Astronomical
Almanac, University Science Books, Sausalito, CA

is the definitive reference.  

Savage, N., 2015: Split Second, Comm. ACM, 58, No. 9, 12-14

deals with "The issue of whether to add a `leap second' to square
the clock with the Earth's orbit pits time specialists against IT."
(quoting from the index to that issue of CACM).

To put it simply, Astronomical Julian Date (and relatives) produces 
a uniform time record in seconds,  It also makes sure that all dates/times
are reduced to the same time zone at the Greenwich meridian.  The usual
IT convention (YYYYMMDD) is non-uniform (for example, Feb. may have 28
or 29 days - while Jul. always has 31).  It would seem that if your
application might move to a geographically distributed environment,
the Julian Date would be sensible.  On the other hand, Julian Date is
not readily interpretable to humans.

Bruce B.