Inconsistency in zoneinfo binary files?

Roland Bock rbock at
Mon Aug 16 14:22:58 UTC 2010

Thanks for the quick and precise response!



On 2010-08-16 15:38, Olson, Arthur David (NIH/NCI) [E] wrote:
>> I am having trouble in comprehending the zoneinfo binary files: I have a
>> version 2 file for Amsterdam which gives me 180 transition times and 13
>> transition types in the first block (all of which look fine to me). But
>> the second block yields 181 transition times and 14 transition types.
>> The additional transition time is 1971-02-07T06:08:44, which seems
>> rather weird to me.
> That's not a bug, it's a feature.-) The key line in the "europe" data file is...
> 	Zone Europe/Amsterdam 0:19:32 - LMT 1835
> ...which tells us that the Netherlands changed its clocks from local mean time
> (different from town to town) to Amsterdam time (throughout the country) at the start of 1835.
> 1835 is so far in the past that it can't be represented by a 32-bit time_t value, but it can be represented by a 64-bit value (as can any instant all the way back to the Big Bang). So the 1835 transition can't be recorded in the first (32-bit) section of the compiled time zone data file, but can be recorded in the second (64-bit) section.
> (The "1971-02-07" comes about when the 1835 transition time is truncated to its low-order 32 bits and fed through 32-bit software.)
> 				--ado

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