<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0"
         xmlns:x="http://www.w3.org/1999/xhtml">

<x:h1>Presentation Module</x:h1>

<define name="hr">
  <element name="hr">
    <ref name="hr.attlist"/>
  </element>
</define>

<define name="hr.attlist">
  <ref name="Common.attrib"/>
</define>

<define name="Block.class" combine="choice">
  <ref name="hr"/>
</define>

<define name="sub">
  <element name="sub">
    <ref name="sub.attlist"/>
    <ref name="Inline.model"/>
  </element>
</define>

<define name="sub.attlist">
  <ref name="Common.attrib"/>
</define>

<define name="sup">
  <element name="sup">
    <ref name="sup.attlist"/>
    <ref name="Inline.model"/>
  </element>
</define>

<define name="sup.attlist">
  <ref name="Common.attrib"/>
</define>

<define name="Inline.class" combine="choice">
  <choice>
    <ref name="sub"/>
    <ref name="sup"/>
  </choice>
</define>

</grammar>