<grammar xmlns="http://relaxng.org/ns/structure/1.0">
<start>
<ref name="inline"/>
</start>
<define name="inline">
<zeroOrMore>
<choice>
<text/>
<element name="code">
<ref name="inline"/>
</element>
<element name="em">
<ref name="inline"/>
</element>
<!-- etc -->
</choice>
</zeroOrMore>
</define>
</grammar>