sub _cmpXML( $$ ){
    # Pass in two XML nodes and return 0 if they are the same, else
    # lexographically compare the namespaces fist then the node names
    # (with out prefexes)
    my $n1 = shift or die;
    my $n2 = shift or die;
    my $ns1 = $n1->namespaceURI();
    my $ns2 = $n2->namespaceURI();
    $ns1 ne $ns2 and return $ns1 cmp $ns2;
    my $nn1 = $n1->nodeName();
    my $nn2 = $n2->nodeName();
    $nn1 =~ s/^[^\:]*:?//;
    $nn2 =~ s/^[^\:]*:?//;
    return $nn1 cmp $nn2;
}