my $root = $this->{zeerex}; # XML::LibXML::Element ISA XML::LibXML::Node
my $xc = XML::LibXML::XPathContext->new($root);
$xc->registerNs(zeerex => "http://explain.z3950.org/dtd/2.0/");
my $root = $this->{zeerex}; # XML::LibXML::Element ISA XML::LibXML::Node
my $xc = XML::LibXML::XPathContext->new($root);
$xc->registerNs(zeerex => "http://explain.z3950.org/dtd/2.0/");