Bill Seymour stdbill.h at
Tue Feb 22 23:23:02 UTC 2011

I had trouble understanding this as well, so I wrote
a little paper about it, mostly for my own benefit:

I've mentioned it a couple of other times on this list,
and nobody has corrected me yet. 8-)

I think that much of the confusion is due to the rules
wanting to be /both/ transitions (most of the rule) /and/
steady states (the SAVE and LETTER columns).  I give
an example in the paper.

Zones are definitely steady states.  My understanding
is that they're in effect during the half-open interval,
[previous line's UNTIL, this line's UNTIL).  If there's
no previous line, the lower bound is the beginning of
time; for the last line, which has no UNTIL, the upper
bound is the end of time. 8-)

Does that make sense?


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