my $root = $doc->getDocumentElement();
my $xc = XML::LibXML::XPathContext->new($root);
$xc->registerNs(e => 'http://explain.z3950.org/dtd/2.0/');
my $root = $doc->getDocumentElement();
my $xc = XML::LibXML::XPathContext->new($root);
$xc->registerNs(e => 'http://explain.z3950.org/dtd/2.0/');