[LEAPSECS] alternative to smearing

[Daniel R. Tobias]

On 6 Jan 2017 at 22:44, Hal Murray wrote:

> I think there are two different types of wait.  One is the simple wait N 
> seconds.  The other is wait until a specified date-time, say a month from 
> now.  They really are different so I don't see how to make your "one 
> interface" work.

It seems you can come up with quite a few "types of wait", or types 
of scheduling for future events, appointments, announcements, and so 
on, all of which ought to be supported in robust calendaring / 
scheduling programs.

* Events scheduled for a fixed point relative to local civil time at 
a specific place; its point in absolute time can change if time zones 
or daylight saving rules shift. Most local events, work shifts, and 
so on are like that.

* A fixed point relative to a particular named time zone, like "U.S. 
Eastern time". National TV networks tend to schedule their broadcasts 
this way. This won't shift in response to time zone boundary changes, 
like if Indiana decides to change time zones between Eastern and 
Central, but will reflect changes in daylight saving shift dates that 
apply zone-wide.

* Fixed point relative to UTC; won't change for time zone and 
daylight saving shifts, but will reflect leap seconds.

* Fixed point relative to a leapless atomic scale such as TAI or GPS; 
its' place relative to UTC will shift for leap seconds, and its place 
relative to local time will shift for leap seconds, daylight saving, 
and time zone shifts.

* Interval-time wait by absolute number of SI seconds (ignoring 
leaps, time zones, and the like).

* Interval-time wait by number of some larger unit such as minutes, 
hours, days, or years as reckoned in some particular time scale; 
there may be leaps built in to it.

Some of these can also be put into some turmoil if more drastic 
calendar-system changes are made such as the Julian/Gregorian shift 
(and any future such thing that might be needed millennia from now 
when the current calendar proves astronomically inadequate).

-- 
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