<?xml version="1.0"?>
<element name="foo"
         xmlns="http://relaxng.org/ns/structure/1.0"
         xmlns:a="http://relaxng.org/ns/annotation/1.0"
         xmlns:ex1="http://www.example.com/n1"
         xmlns:ex2="http://www.example.com/n2">
  <a:documentation>A foo element.</a:documentation>
  <element name="ex1:bar1">
    <empty/>
  </element>
  <element name="ex2:bar2">
    <empty/>
  </element>
</element>