<grammar xmlns="http://relaxng.org/ns/structure/1.0">

  <start>

    <element name="p">

      <ref name="inline"/>

    </element>

  </start>

  <define name="inline">

    <zeroOrMore>

      <choice>

        <text/>

        <element name="bold">

          <ref name="inline"/>

        </element>

        <element name="italic">

          <ref name="inline"/>

        </element>

        <element name="span">

          <optional>

            <attribute name="style"/>

          </optional>

          <ref name="inline"/>

        </element>

      </choice>

    </zeroOrMore>

  </define>

</grammar>