<?xml version="1.0"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0">
  <start>
    <element name="test" ns="http://example.com/1/">
      <zeroOrMore>
        <attribute>
          <choice>
            <nsName ns="http://example.com/1/"/>
            <nsName ns="http://example.com/2/"/>
          </choice>
          <text/>
        </attribute>
      </zeroOrMore>
    </element>
  </start>
</grammar>