Single column from the root: 

my @lats =
    map $_->getValue(),
    $root->findnodes('//datacolumn[@name="Latitude"]/item/@value');

[download]

All columns: 

my %table;
#for my $col_node ( $root->findnodes('//datacolumn') ) {
for my $col_node ( $table_node->findnodes('datacolumn') ) {
    my $col_name = $col_node->getAttribute('name');
    $table{$col_name} = [
        map $_->getValue(),
        $col_node->findnodes('item/@value')
    ];
}

[download]

I assumed the elements are in the null namespace.

Update: Added second snippet.
Update: s/name=/\@name=/

In reply to Re: XML::LibXML extracting datacolumn by ikegami
in thread XML::LibXML extracting datacolumn by deadpickle

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