my $xpc = XML::LibXML::XPathContext->new( $doc );
$xpc->registerNs( ota => 'http://www.opentravel.org/OTA/2003/05' );
my @options = $xpc->findnodes('//ota:OriginDestinationOption');

##</code><code>##

# Doesn't work because OriginDestinationOption belong to
# the http://www.opentravel.org/OTA/2003/05 NS, not the
# null NS.

my $root = $doc->documentElement();
my @opts = $root->findnodes("//OriginDestinationOption");

##</code><code>##

# Doesn't work because OriginDestinationOption element
# appears as <OriginDestinationOption>, rather than
# <ota:OriginDestinationOption>

my $root = $doc->documentElement();
my @opts = $root->findnodes("//ota:OriginDestinationOption");

##</code><code>##

my $root = $doc->documentElement();
my @opts = $root->findnodes("//*[name()="OriginDestinationOption"]');