<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0"
         ns="http://www.olympus.com">
    <start>
        <choice>
            <ref name="lensDefn"/>
            <ref name="zoomDefn"/>
            <ref name="f-stopDefn"/>
        </choice>
    </start>
    <define name="lensDefn">
        <element name="lens">
            <ref name="zoomDefn"/>
            <ref name="f-stopDefn"/>
        </element>
    </define>
    <define name="zoomDefn">
        <element name="zoom">
            <text />
        </element>
    </define>
    <define name="f-stopDefn">
        <element name="f-stop">
            <text/>
        </element>
    </define>
</grammar>