You can retrieve the namespace by the namespaceURI method: 
my $doc   = XML::LibXML->load_xml(location => '1.xml');
my $root  = $doc->documentElement;
my $nsuri = $root->namespaceURI;

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You have to register the namespace before you can use it. It is annoying, but it is how XML works: if no namespace is specified, it means the empty namespace, not a default one (imagine the main:: package in Perl having no name).

If you find XML::LibXML too verbose (as I do), you might like XML::XSH2 which is a simple wrapper around it which reduces most of the incantations. Nevertheless, you still have to 

register-namespace gt http://www.govtalk.gov.uk/CM/envelope ;

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لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

In reply to Re: LibXML, XPath and Namespaces by choroba
in thread LibXML, XPath and Namespaces by space_monk

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