Description:
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The ISO-8601 states the following: "The offset from UTC is given in the format ±[hh]:[mm], ±[hh][mm], or ±[hh].". But DatePeriod accepts only $iso formats that are in UTC (flag Z). See test script.

I have tried all possible combinations to set timezone correctly, but no success:
http://en.wikipedia.org/wiki/ISO_8601#Time_zone_designators

Test script:
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<?php
$iso = 'R2/2013-09-09T12:00:15Z/P1D';
$periods = new DatePeriod($iso);
var_dump( is_object($periods) );

$iso = 'R2/2013-09-09T12:00:15+02:00/P1D';
$periods = new DatePeriod($iso);
var_dump( is_object($periods) );



Run this on multiple PHP versions: http://3v4l.org/b4n9j

Expected result:
----------------
bool(true)

bool(true) # with correct offset ofc

Actual result:
--------------
bool(true) 

Fatal error: Uncaught exception 'Exception' with message 'DatePeriod::__construct(): Unknown or bad format (R2/2013-09-09T12:00:15+02:00/P1D)' in ...