The daylight savings time flag ("$dst") will be "-1" if this
information is not available on your system, "0" for no daylight
savings time (i.e., winter time) and "1" when daylight savings
time is in effect.

##</code><code>##

#!/usr/bin/perl

use Date::Calc qw (:all);

$summer_time = Mktime (2012, 7, 3, 1, 48, 0);
$winter_time = Mktime (2012, 12, 3, 1, 48, 0);
($year,$month,$day, $hour,$min,$sec, $doy,$dow,$dst)
    = Gmtime ($summer_time);
print "Summer: $year,$month,$day,$hour,$min,$sec,$doy,$dow,$dst\n";
($year,$month,$day,$hour,$min,$sec,$doy,$dow,$dst)
    = Gmtime ($winter_time);
print "Winter: $year,$month,$day,$hour,$min,$sec,$doy,$dow,$dst\n";
__END__
Results:

Summer: 2012,7,3,5,48,0,185,2,0
Winter: 2012,12,3,6,48,0,338,1,0