Script detail 

• adds content to the data structure

$data->{$area_name}{$track_num}{coordinates}{$key}{lat} = [@lat];
$data->{$area_name}{$track_num}{coordinates}{$key}{long} = [@long];

• outputs kml looping through the datstructure

foreach my $area (sort keys %{$data}) {

    my $area_folder = $dom->createElement('Folder');
    $areas_folder->appendChild($area_folder);
    ...
}