test/relaxng/pattern1.rng - third_party/libxml2 - Git at Google

 <group xmlns="http://relaxng.org/ns/structure/1.0">
   <element name="a">
     <text/>
   </element>
   <element name="b">
     <text/>
   </element>
 </group>
	<group xmlns="http://relaxng.org/ns/structure/1.0">
	<element name="a">
	<text/>
	</element>
	<element name="b">
	<text/>
	</element>
	</group>