<xsd:attributeGroup id="attGp.formula" name="formula">
    <xsd:attribute id="att.formula" name="formula" type="formulaType">
        <xsd:annotation>
            <xsd:documentation>
                <h:div class="summary" xmlns:h="http://www.w3.org/1999/xhtml">Simple chemical formula.</h:div>
                <h:div class="general" xmlns:h="http://www.w3.org/1999/xhtml">
This attribute should only be used for simple formulae (i.e. without brackets or other nesting for which a _formula_ child element should be used. The attribute might be used as a check on the child elements or for ease of representation. Essentially the same as _concise_ attribute on _formula.</h:div>
            </xsd:documentation>
        </xsd:annotation>
    </xsd:attribute>
</xsd:attributeGroup>