A sample xml file to demonstrate ruby libxml's reader api.

sample.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<nex:nexml 
	version="0.8"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.nexml.org/1.0 ../xsd/nexml.xsd"
	xmlns:nex="http://www.nexml.org/1.0"
	generator="mesquite"
	xmlns:xlink="http://www.w3.org/1999/xlink"
	xmlns="http://www.nexml.org/1.0">
	<otus 
		id="taxa1" 
		label="My taxa block" 
		xml:base="http://example.org/" 
		xml:id="taxa1" 
		class="taxset1" 
		xml:lang="EN" 
		xlink:href="#taxa1">
		<!--  
			The taxon element is analogous to a single label in 
			a nexus taxa block. It may have the same additional
			attributes (label, xml:base, xml:lang, xml:id, xlink:href
			and class) as the taxa element.
		-->
		<otu id="t1"/>
		<otu id="t2"/>
		<otu id="t3"/>
		<otu id="t4"/>
		<otu id="t5"/>
	</otus>
</nex:nexml>