DateTime and Excel difference
Seems that DateTime module thinks 29.2.1900 didn't exist while Excel 2008 does. Which one is correct ? Well DateTime is OpenSource while Excel is payware. Think payware would be correct ? nope, DateTime is !
So the correct DateTime object for dates starting 1.3.1900 when using values from Excel is :
DateTime->new(year=>1900, month =>1, day => 1) ->add(days=>$THEVALUEFROMEXCEL-2)