proposed change to 'zic' to support "outlandish" offsets

Steven R. Loomis srl at
Tue May 1 18:55:20 UTC 2007

   I've been following this discussion with interest, and we have  
discussed it a bit on the ICU mailing list (which is an application  
library which does time zone and calendar calculations, among other  
   What would be ideal is not to change the system clock to be  
'back', but to have the default calendar used by all formatters/ 
parsers to be a Julian one.  ( i.e. as opposed to Gregorian,  
Japanese, etc. ) .  One major benefit of this is that otherwise  
communication in and out (such as email dates..) will be all wrong.    
Time zone calculations could be simply done according to the  
Gregorian calendar ( to not affect either ICU or TZ infrastructure )   
with the gregorian dates for changeover, whether the intended  
changeovers are in J or G time.   (similar to how Israel time is  
handled, for example.)  In other words, Athos time's zone rules could  
be in the TZ database according  to the Gregorian dates of DST  
changes. Or would it follow Greece's DST rules?

   I think that having an outlandish offset would complicate things  
more than simply recalculating day of week, day of month, etc.  based  
on a different calendar system, as if it were the Hebrew or Islamic  
or Hindi calendar.


On 01 Mej 2007, at 06:37, Olson, Arthur David ((NIH/NCI)) [E] wrote:
> I don't know about Mt. Athos in particular; the general case of trying
> to support Julian dates is complicated by needing to change the
> day-of-month associated with a time_t value without changing the
> day-of-week associated with the value.
> The advent of the 64-bit time_t extends the range of time_t values to
> include historical periods when the Julian calendar was in effect. It
> may or may not be worthwhile to try to change the handling of  
> Julian-era
> time_t values; doing so would seem to require changes to both zic  
> and to
> localtime.
> 				--ado
> -----Original Message-----
> From: Paul Eggert [mailto:eggert at]
> Sent: Monday, April 23, 2007 6:37 PM
> To: tz at
> Cc: mgpeter at; evdokimos at
> Subject: proposed change to 'zic' to support "outlandish" offsets
> Currently zic allows only GMT offsets in the range -24:00 to 24:00.
> And yet the recent query about Mt. Athos led me to think that in some
> cases it can be useful to allow GMT offsets outside the range, to
> approximate the Julian calendar.  And at any rate zic should be able
> to generate whatever offset can be stored in the standard tz file
> format, if only for testing purposes.

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