#!/usr/bin/perl -w

use strict;
use XML::Generator;

my $gen = XML::Generator->new(
    conformance => 'strict',
    escape      => 'always',
    pretty      => 2,
    encoding    => 'UTF-8',
    version     => '1.0',
    namespace   => [itunes => "http://www.itunes.com/dtds/podcast-1.0.
+dtd"],
);

print $gen->xmldecl('standalone' , undef);
print    $gen->rss([itunes => "http://www.itunes.com/dtds/podcast-1.0.
+dtd"], {version => '2.0'});
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<?xml version="1.0" encoding="UTF-8"?>
<itunes:rss xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd" 
+version="2.0" />
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In your example, you don't want the <rss> tag to be in the itunes: namespace, so you shouldn't be passing in a namespace to the corresponding XML::Generator call. All you need to do to get the xmlns:itunes attribute into the <rss> tag is to use that namespace in some embedded content. For example:

  $itunes = XML::Generator->new(namespace=>[itunes=>'http://...']);
  $gen = XML::Generator->new();

  print $gen->rss($itunes->author("Some Guy"))
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This generates:

<rss xmlns:itunes="http://..."><itunes:author>Some Guy</itunes></rss>
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