Robert Elz kre at munnari.OZ.AU
Tue Feb 22 15:44:16 UTC 2011

    Date:        Tue, 22 Feb 2011 13:19:26 +0000
    From:        jrl <jrl at>
    Message-ID:  <E468A544C5BEF74DBF22CAAB3FD50DE810F48C13 at UNIVERZ.terraatlas.local>

  | Meaning use the Macau rules until Dec 20, 1999
  | There are no Macau Rules after October of 1980.


  | SO... in my mind it means we revert to the overall rule of the Zone

No, no rules means no transitions, the time just continues forward
(like the clock on your wall) without any strange jumps.   Whenever the
time jumps, we need a transition point, the rules say when those
transition points appear.

  | If there are no rules, then revert back to the rule of the Zone.

Where do you think the documentation says that?   Because if there is
somewhere, we need to fix it, because that's not how it works at all.
The rules give the method for finding the transition points, when there is
no transition point, time just moves forward, as time always has.

  | What doesn't make sense if why a set of Rules is used that ends prior
  | to the end of the period used by the zone.

Because there was a period when there were transitions, and that period
ended, the rules cover the period of transitions.

  | Perhaps a "max" in place of the 1980 would make this more clear.

No, just the opposite.  We use "max" when we have transitions that
are continuing into the future, to some (as yet) undetermined future time.
When we know when the transitions stopped occurring, we say so, that is
what makes things clear.

Once again, the point of the rules is to provide a method by which we
calculate the points at which local wallclock time experiences a 
non-continuity, and that's it.   Nothing else is reasonably possible,
as these things are not necessarily nice nested "go forward and back"
operations that could be expressed using other means.


ps: you said "the time change ran ends on the Sunday before the 15th
for the years 1978, 1979, and 1980" whereas the rule you quoted in the
earlier mail was "the first sunday on or after the 15th" (Sun>=15) (a
way of saying "the third sunday") - I assume the "before" in your message
was just a typo/thinko.

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