definition of correctness

Hi Guys,

I have a peculiar issue wrt datetime arithmetic involving DST boundary.

perl -MDateTime -le '$dt = DateTime->new(day => 4, month => 10, year
=> 2008, hour => 2, time_zone => "Australia/Melbourne"); print
$dt->add(hours => 48)'

gives different results compared to

perl -MDateTime -le '$dt = DateTime->new(day => 4, month => 10, year
=> 2008, hour => 2, time_zone => "Australia/Melbourne"); print
$dt->add(days => 2)'

although the latter seems consistent with what POSIX::mktime does. The
question I have is about the correctness of DST calculations and
whether POSIX::mktime is busted.

Note:
1. AEST DST switch happens on Oct 5 2008 at 0200
2. using POSIX::mktime, +24 hrs gives you 3am on Oct 5th 2008 but
+25hrs gives you the same time as well.

any help on clarifying this would be much appreciated.

thanks
cheers,
Bharanee