# Re: decision tree for civil time

From: Rob Seaman <seaman_at_noao.edu>
Date: Sat, 13 Aug 2005 13:31:56 -0700

I've incorporated Poul-Henning Kamp's good suggestions as follows:

> I would have thought this would be:
>
> 1) correction issued as table
> 2) correction issued as formula

I think that's an orthogonal category called "corrections". Updates
to the table or formula can still occur on either a fixed or as-
needed schedule.

> 3) maximize scheduling horizon.

That's one of the issues with leap hours - it's easy to maximize a
schedule, simply never do something. I believe this is really a
question of imposing a fixed schedule that happens to be of long
duration. Perhaps I misunderstood your point.

Thanks for playing along.

Rob Seaman
National Optical Astronomy Observatory
```---
Please remark on any gaps you see, especially missing categories:
I) Existence
A) adopt a civil time standard
B) no civil time standard
II) Multiplicity
A) a single international civil time standard
B) multiple civil time standards
III) Locale
A) restrict focus to Earth
B) Solar system-wide solution
C) Universe-wide solution.
IV) Synchronization
A) Type
1) Solar
2) Atomic
3) Other (e.g., sidereal, lunar, dynamical, relativistic, ...)
1) None
2) Dual (e.g., UTC is synchronized to both Solar and Atomic
scales)
3) Multiple (e.g., Earth+Mars+Atomic)
C) Method
1) steps (I'm tired of the word "leap)
a) arbitrary size
b) fixed size
i) second
ii) minute
iii) hour
iv) other
2) rates ("rubber seconds")
3) both
D) Triggering
1) manual (e.g., reset a clock by hand)
2) automatic
1) discontinuity
2) time slice (e.g., UTS)
F) Scheduling
1) as needed
G) Corrections
1) issued as table
2) issued as formula
3) implicit in method
H) Optimization
1) remain within tolerance (e.g., 0.9s)
2) minimize figure of merit (e.g., DUT1)
I) Frequency
1) continuously
2) daily
3) monthly
4) annually