When I originally wrote our compiler for this file format, I also had troubles understanding it. I think the item which I found most confusing was the choice of words for 'RULE' and 'ZONE'. In my mind now ZONE is in more than anything else 'an offset and set of D/S rules' to apply, whereas RULE is more than anything else 'a transition point for D/S within that set of rules' On 2011-02-22 08:00, Robert Elz wrote:
Date: Tue, 22 Feb 2011 11:14:18 +0000 From: jrl<jrl@terraatlas.com> Message-ID:<E468A544C5BEF74DBF22CAAB3FD50DE810F47BBB@UNIVERZ.terraatlas.local> | What is the correct rule for Macau from 1980 through 1999? | Did they return to LMT?
I wonder if there is any way we can make the documentation clearer that the rules do not specify intervals, but transition points.
People keep asking questions (like this one) that make no sense at all if the rules are interpreted correctly, but would be perfectly legitimate if the rules were doing something like "specifying the period when summer time applies".
Since this mistake is so commonly made, it must be a problem with the tz documentation. Unfortunately, I can't see it (which is often true when someone who knows the answer tries to see why others cannot see it).
Does anyone have any ideas how we can make this clearer? Is the problem that people are just reading the data files, and ignoring the documentation? Do we need to add some explanatory comments in every data file?
kre
ps: the Macau rules say that the last time there was a std/summer time transition in Macau was the 3rd SUn in October, 1980, since then the only change has been the change of time zone abbreviation when Macau became part of China again. So, no, it dod not revert to LMT, there simply were no more transitions - and once you understand that the rules are used to specify transition points, this is really all very obvious.