Re: Leap Seconds

["Marin David Condic" <marin.condic.auntie.spam@pacemicro.com>]

Further research into leap-seconds indicates that effectively, they are
unpredictable. The International Earth Rotation Service sort of announces
them whenever they think it is necessary and they can be positive or
negative. Hence, unless one has a lookup table for leap-seconds in the past,
it would not be possible to know when they existed. (The first happened in
1972) It is even more problematic if you are calculating some time in the
future since you don't know when they happen. (Customarily, leap-seconds are
announced in December or June, but they need not happen every year.)

While a handful of seconds over a number of years may not be a big deal in
most cases, I could easily imagine where they might make a difference.
(Especially when trying to sync up with something else that is using a time
base somewhere in the past and wondering if it counts the leap seconds and
you don't. Source A counts them, source B doesn't and you're in the middle
trying to figure out 'does anybody really know what time it is?')

More info at:

http://maia.usno.navy.mil/eo/leapsec.html

Now I'm wondering what I'm supposed to do with the requirement that I count
them??? :-)

MDC
--
Marin David Condic
Senior Software Engineer
Pace Micro Technology Americas    www.pacemicro.com
Enabling the digital revolution
e-Mail:    marin.condic@pacemicro.com
Web:      http://www.mcondic.com/


"Tucker Taft" <stt@averstar.com> wrote in message
news:3B0ED67B.E40A4E06@averstar.com...
>
> There is no requirement to support leap seconds.
> I would guess it is safe to say that leap seconds
> are *not* supported in any Ada implementation.
> There might even be ACATS/ACVC tests that are actively unfriendly
> to leap seconds, though I don't know for sure.
>