[tz] McMurdo/South Pole

Lester Caine lester at lsces.co.uk
Mon Sep 23 08:48:58 UTC 2013

Guy Harris wrote:
> On Sep 22, 2013, at 9:57 PM, Lester Caine <lester at lsces.co.uk> wrote:
>> A similar situation has now been created in the PHP API, which has also been switched to using TZ as the 'bible' when it comes to DST information. So the above statement applies ... except that the TZ data needs to return 'invalid' when a request is made that it can not process.
> Such as any request for information given a date/time prior to the establishment of some form of standard time in the specified tzdb zone.
>> So that we can then revert to an alternate lookup.
> There do not appear to be any APIs in
> 	http://www.php.net/manual/en/refs.calendar.php
> that take a longitude (and perhaps latitude) as an argument, so there's nothing those APIs can do to convert times prior to the establishment of standard time.

DateTimeZone was added in PHP5.2 ... There were problems when it was introduced 
since the original attempt trod on the toes of older tools which did things 
differently. DateTimeZone was introduced using the TZ data as it's reference 
source, but currently there is no warning that while DateTime transparently goes 
back in time, and it REQUIRES that a timezone is set, the data returned prior to 
1970 may not be appropriate. Obviously this is not a problem that TZ would 
accept, but it demonstrates that end users - such as myself! - would have no 
idea that there WAS a problem until we dug deeper. PHP's documentation needs an 
update, but we still have the problem of plugging this hole going forward?

Lester Caine - G8HFL
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