<xsd:simpleType name="headType" id="st.headType">
    <xsd:annotation>
        <xsd:documentation>
            <h:div class="summary" xmlns:h="http://www.w3.org/1999/xhtml">The head linker in a polymeric repeat unit</h:div>
            <h:div class="description" xmlns:h="http://www.w3.org/1999/xhtml">
                <h:p>A polymeric chain may be described by liniing the head of one repeat
                unit to the tail or head of another. The head attribute indicates the atom
                id (normally on an atom of elementType="R") which acts as the head</h:p>
            </h:div>
            <h:div class="curation" xmlns:h="http://www.w3.org/1999/xhtml">2006-05-20: PMR added</h:div>
            <h:div class="example" href="headType1.xml" xmlns:h="http://www.w3.org/1999/xhtml" />
        </xsd:documentation>
    </xsd:annotation>
    <xsd:restriction base="xsd:string">
        <xsd:pattern value="[A-z][A-z0-9_]*" />
    </xsd:restriction>
</xsd:simpleType>