Here's a working exaple:

use XML::Simple;

my $data = <<'__EOI__';
<?xml version="1.0" encoding="us-ascii"?>
<?xml-stylesheet type="text/xsl" href="Adminproduct.xsl"?>
<category name="Coffee">
        <heading>150 years of know how at the service of a same strate
+gy: Taste</heading>
        <photo>images/bag_legal.jpg</photo>
        <comments>
          <paragraph>Roaster since 1851</paragraph>
          <paragraph>A revolution in the packaging arena</paragraph>
        </comments>
        <subcategory name="Prestige">
            <comments><paragraph>Prestige is a very traditional French
+ recipe</paragraph>
            </comments>
            <photo>images/prestige.jpg</photo>
            <product>Coffee
                <channel>D</channel>
                <channel>A</channel>
                <product_id>800.55.01</product_id>
                <brand>Legal</brand>
                <description>Legal Prestige</description>
                <conditionning unit="gr">250</conditionning>
                <packaging_qty>12</packaging_qty>
                <recipe>/recipes/coffee1.html</recipe>
            </product>
            <product>Coffee
                <channel>D</channel>
                <channel>A</channel>
                <product_id>801.55.01</product_id>
                <brand>Legal</brand>
                <description>Legal Prestige Boite Ar&#xF4;me</descript
+ion>
                <conditionning unit="gr">500</conditionning>
                <packaging_qty>6</packaging_qty>
            </product>
        </subcategory>
</category>
__EOI__

# In older versions:
$category = XMLin($data, forcearray=>1);
XMLout($category, rootname =>'category', outputfile => \*STDOUT);

# In newer versions:
#$category = XMLin($data, ForceArray=>1);
#XMLout($category, RootName =>'category', OutputFile => \*STDOUT);

__END__
output
======
<category name="Coffee">
  <subcategory name="Prestige">
    <photo>images/prestige.jpg</photo>
    <product>Coffee
                <packaging_qty>12</packaging_qty>
      <product_id>800.55.01</product_id>
      <conditionning unit="gr">250</conditionning>
      <brand>Legal</brand>
      <channel>D</channel>
      <channel>A</channel>
      <recipe>/recipes/coffee1.html</recipe>
      <description>Legal Prestige</description>
    </product>
    <product>Coffee
                <packaging_qty>6</packaging_qty>
      <product_id>801.55.01</product_id>
      <conditionning unit="gr">500</conditionning>
      <brand>Legal</brand>
      <channel>D</channel>
      <channel>A</channel>
      <description>Legal Prestige Boite Ar¶me</description>
    </product>
    <comments>
      <paragraph>Prestige is a very traditional French recipe</paragra
+ph>
    </comments>
  </subcategory>
  <photo>images/bag_legal.jpg</photo>
  <heading>150 years of know how at the service of a same strategy: Ta
+ste</heading>
  <comments>
    <paragraph>Roaster since 1851</paragraph>
    <paragraph>A revolution in the packaging arena</paragraph>
  </comments>
</category>
[download]

Thank you very much for your help. I found another way which I use this"

#!C:\PERL\bin\perl.exe


use strict;
use CGI ':standard';
use XML::Simple;

    #Variables
    
    my $arrays = [qw/subcategory packaging_qty recipe description prod
+uct paragraph comments channel brand conditionning product_id heading
+ photo/];
    my $cat = 'C:\Program Files\Apache Group\Apache2\htdocs\legastrono
+me\XML\Admin\test4.xml';

    my $category = XMLin( (join'', $cat), KeyAttr => 1, 'ForceArray' =
+> $arrays);
        
                    XMLout($category, rootname =>'category', outputfil
+e =>('C:\Program Files\Apache Group\Apache2\htdocs\legastronome\XML\A
+dmin\test4.xml'));
[download]

I can say it works well. I found your way better because there is less code. But I need now to put the first two lines at the begin. I am still trying. Again thanks. Really this website is the best.