Hello, better you forget XML::Simple, may be you'll instead find useful XML::Twig
In the TIMTOWTDI spirit i present a simple XML::Twig solution:

#!/usr/bin/perl

use strict;
use warnings;
use XML::Twig;



my $twig=XML::Twig->new( pretty_print => 'indented',
                         twig_handlers => {
                          'GfmDocument/GfmHeader/TopicMessageID ' => s
+ub{print $_[1]->text,"\n";},
                          
                          '/GfmDocument/GFMIEDM35/OBJ_ITEM_OO_TBL/OBJ_
+ITEM' =>  sub{
                                       my $twig = shift;
                                       my $obj =shift;
                                       print map { "\t".$obj->first_ch
+ild_text($_)."\n" } qw(OBJ_ITEM_ID CAT_CODE NAME_TXT);
                                       my $org = $obj->first_child('OR
+G');
                                       print map { "\t".$org->first_ch
+ild_text($_)."\n" } qw(ORG_ID CAT_CODE GFM_CAT_CODE);
                                       print "\n\n";

                          },
                        },


);
$twig->parsefile( 'xmlpmonks.xml') or die; # build it


__END__
#output
2754
        72060793789255493
        OR
        Oranization 10
        72060793789255493
        UN
        NOS


        72060793789255508
        OR
        Organization 25
        72060793789255508
        UN
        NOS


        72060793789255510
        OR
        Organization 50
        72060793789255510
        UN
        NOS
[download]

hth

L*