To use namespaces in the full depth, use XML::LibXML::XPathContext: 
#!/usr/bin/perl
use warnings;
use strict;

use XML::LibXML;

my $xpc  = XML::LibXML::XPathContext->new();
my $xml  = XML::LibXML->load_xml(IO => *DATA);
my $root = $xml->documentElement;
$xpc->registerNs('xlink', 'http://www.w3.org/1999/xlink');
my $chapter_node = $xpc->findnodes('book:chapter', $root)->[0];
print $xpc->findvalue('book:locator/@xlink:title | book:locator/@xlink
+:href', $chapter_node) . "\n";

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In reply to Re^6: How to parse xml with namespase vale in XMl:LibXML? (xmllint --shell setns / xpathtester) by choroba
in thread How to parse xml with namespase value in XMl:LibXML? by ravi06

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