Question on interpretation of rules intervals

Moore, Martin martin.moore at
Mon Apr 2 14:27:44 UTC 2007

Here's how I interpret it:

"War Time" (1 hour advanced) stayed in effect from Feb 9, 1942, through
1943 and 1944 and into 1945.  On August 14, 1945, the name (only)
changed from "War Time" to "Peace Time", since hostilities had ended.
The time was still one hour advanced.  This continued until September
30, 1945, when Standard Time resumed. 


-----Original Message-----
From: Liviu Nicoara [mailto:nicoara at] 
Sent: Monday, April 02, 2007 10:17 AM
To: tz at
Subject: Question on interpretation of rules intervals

Hi all,

I have a question about how to interpret the US set of rules. After
going through the "zic" man page and the mailing list archive I am still
unclear about the meaning of using this:

Rule US 1942 only - Feb  9 2:00   1:00 W # War
Rule US 1945 only - Aug 14 23:00u 1:00 P # Peace
Rule US 1945 only - Sep 30 2:00      0 S

in a zone definition like this:

Zone America/New_York -4:56:02 -  LMT  1883 Nov 18 12:03:58
                       -5:00   US  E%sT 1920
                       -5:00   NYC E%sT 1942
                       -5:00   US  E%sT 1946

As I see it, the US rule has a transition in 1942 (only), on Feb 9th,
where it saved 1 hour. Am I correct in interpreting the gap of 43-44 as:

1. The transition of 1942 was observed up until 1945, Sep 30th, and...
2. The entry for Aug 14th, 1945 transition exists only in order to be
    used in time zones which did not observe the 1942 transition?


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