1 <element name="root" xmlns="http://relaxng.org/ns/structure/1.0">

     2   <oneOrMore>

     3     <element name="subelement">

     4       <choice>

     5         <element name="a">

     6 	  <text/>

     7 	</element>

     8 	<zeroOrMore>

     9 	  <element name="b">

    10 	    <empty/>

    11 	  </element>	  

    12 	  <element name="c">

    13 	    <empty/>

    14           </element>	  

    15 	</zeroOrMore>

    16       </choice>

    17     </element>

    18   </oneOrMore>

    19 </element>