Rules for Asia/Tokyo and Asia/Karachi
joe at mcknight.de
Mon Aug 23 22:10:47 UTC 2010
I am trying to understand the database file format and have a question
regarding the rule definition of Asia/Tokyo and Asia/Karachi. Both
time zones seem to be valid but I cannot see that from their
definition in the database.
Let's look at Asia/Tokyo only, but Asia/Karachi is similar...
# Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
Rule Japan 1948 only - May Sun>=1 2:00 1:00 D
Rule Japan 1948 1951 - Sep Sat>=8 2:00 0 S
Rule Japan 1949 only - Apr Sun>=1 2:00 1:00 D
Rule Japan 1950 1951 - May Sun>=1 2:00 1:00 D
# Zone NAME GMTOFF RULES FORMAT [UNTIL]
Zone Asia/Tokyo 9:18:59 - LMT 1887 Dec 31 15:00u
9:00 - JST 1896
9:00 - CJT 1938
9:00 Japan J%sT
So Asia/Tokyo references the ruleset "Japan" which is only defined for
the years 1948 - 1951. Wouldn't that mean that Asia/Tokyo is only
valid during those years? Especially, it references a substring with
"J%sT", where does this substring come from for any other year?
Thanks a lot,
More information about the tz