<xsd:simpleType name="isotopeType" id="st.isotopeType">
    <xsd:annotation>
        <xsd:documentation>
            <h:div class="summary" xmlns:h="http://www.w3.org/1999/xhtml">The numeric representation of an isotope.</h:div>
            <h:div class="description" xmlns:h="http://www.w3.org/1999/xhtml">
                <h:p>In core CML this represents a single number; either the 
         combined proton/neutron count or a more accurate estimate of the 
         nuclear mass. This is admittedly fuzzy, and requires a more complex
         object (which can manage conventions, lists of isotopic masses, etc.)
         See <h:a href="el.isotope">isotope</h:a>.</h:p>
                <h:p>The default is "natural abundance" - whatever that can be interpreted
         as.</h:p>
                <h:p>Delta values (i.e. deviations from the most abundant istopic mass)
         are never allowed.</h:p>
            </h:div>
        </xsd:documentation>
    </xsd:annotation>
    <xsd:restriction base="xsd:double">
        <xsd:minInclusive value="0.0" />
        <xsd:maxInclusive value="99999999999.0" />
    </xsd:restriction>
</xsd:simpleType>