Re: decision tree for civil time

[Rob Seaman]

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, ...)     B) Overloading         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     E) Adjustment         1) discontinuity         2) time slice (e.g., UTS)     F) Scheduling         1) as needed         2) fixed in advance     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         5) decade         6) century         7) greater than a century     J) Notification         1) monthly         2) six months         3) annually         4) decade         5) fifty years         6) surprise