#!/bin/perl -w
use strict;
use XML::Twig;

 my $twig=new XML::Twig(twig_roots => {'TEXT' =>1} ,twig_handlers=>{'REF' => \&REF}); # change the address of root to TEXT element because REF is the children of TEXT
 my $field='REF';
$twig->parsefile("AFP_ENG_20050316.0102.xml"); #Parse the file
 my $root=$twig->root;
 my $rootchild=$root->children;

sub REF
{
 my ($twig ,$field)=@_;
 my $extension = $field->text;#keep the value of REF element
 my $att=$field->att('EXT');  #keep the value of Ext ( some REF elements do not have EXT attribute) 
 print "$extension\n";
 $att->set_text($field);
 $extension=$att;
}
$twig->print;