Civil Time decision tree v0.5

From: Rob Seaman <>
Date: Sun, 14 Aug 2005 13:18:27 -0700

Revised and rearranged. Decided a version number was prudent - v0.5
since I figure we're half way there. Reminder - the intent is to
provide a scaffolding for characterizing any possible civil time
standard (whether practical or not).

Rob Seaman
National Optical Astronomy Observatory
I) Existence [Adopt an international (or intergalactic) civil time
     A) yes
     B) no
II) Multiplicity [How many standards?]
     A) one
     B) many
For each civil time standard:
III) Locale
     A) restricted to Earth [projects or users, not necessarily
     B) other than Earth [e.g., Martian rovers]
     B) Solar system scope
     C) truly Universal
IV) Synchronization [with underlying time standard(s)]
     A) Overloading
         1) Single
         2) Dual [e.g., UTC is synchronized to both Solar and Atomic
         3) Multiple [e.g., Earth+Mars+Atomic]
     For each fundamental standard:
     B) Phenomenology
         1) Natural
             s) Solar
                 i) apparent
                 ii) mean
                 iii) standard
                 iv) daylight saving
                 v) Sidereal
             b) Tidal
             c) Lunar
             d) Seasonal
             e) Planetary
                 i) various
         2) Physical
             a) Atomic
             b) GPS
         3) Dynamical [roughly both]
             a) various
     C) Optimization
         1) remain within tolerance (e.g., 0.9s)
         2) minimize figure of merit (e.g., DUT1)
         3) minimize uncertainty in schedule
     D) Method
         1) steps (I'm tired of the word "leap)
             a) arbitrary size
             b) fixed size
                 i) millisecond
                 ii) second
                 iii) minute
                 iv) hour
                 v) other
         2) rates ("rubber seconds")
         3) both
     E) Adjustments
         1) discontinuity
         2) time slice (e.g., UTS)
     F) Triggering
         1) manual (e.g., reset a clock by hand)
         2) automatic
     G) Scheduling
         1) adaptive as needed
         2) sliding
         3) fixed in advance
     H) Sampling
         1) continuous
         2) daily
         3) monthly
         4) annually
         5) decadal
         6) pre century
         7) greater than a century
         8) arbitrary
     I) Corrections
         1) issued as table
         2) issued as formula
         3) implicit in method
     J) Residuals [e.g., DUT1]
         1) None
         2) Fixed
         3) Monotonic
         4) Periodic
         5) Piecewise
         6) Arbitrary
     K) Notification
         1) as needed
         2) daily
         3) monthly
         4) six months
         5) annually
         6) decade
         7) fifty years
         8) none needed
Received on Sun Aug 14 2005 - 13:18:53 PDT

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