1<element name="number" xmlns="http://relaxng.org/ns/structure/1.0">
2   <attribute name="val">
3      <list>
4         <oneOrMore>
5            <choice>
6               <value>1</value>
7               <value>2</value>
8               <value>3</value>
9            </choice>
10         </oneOrMore>
11      </list>
12   </attribute>
13   <text/>
14</element>
15