1<element name="doc" xmlns="http://relaxng.org/ns/structure/1.0">
2  <interleave>
3    <element name="a">
4      <empty/>
5    </element>
6    <zeroOrMore>
7      <element name="b">
8        <empty/>
9      </element>
10    </zeroOrMore>
11  </interleave>
12  <element name="c">
13    <empty/>
14  </element>
15</element>
16