[tz] Precise meaning of FROM and TO in a rule

[Paul Eggert]

Transitions are given in terms of the local time before the transition, 
as otherwise a transition could be self-referential.  A single rule can 
specify multiple transitions, and it's reinterpreted each time it's used.

Perhaps the following change to zic.8?

diff --git a/zic.8 b/zic.8
index fb8f882..bd9dfeb 100644
--- a/zic.8
+++ b/zic.8
@@ -283,6 +283,7 @@ or
  if the given time is universal time;
  in the absence of an indicator,
  wall clock time is assumed.
+Local time and date is interpreted as of just before the rule takes effect.
  .TP
  .B SAVE
  Gives the amount of time to be added to local standard time when the 
rule is in