<xsd:element minOccurs="0" maxOccurs="1" name="value" nillable="true">
    <xsd:complexType>
        <xsd:sequence>
            <xsd:element minOccurs="0" maxOccurs="1" name="visibility" nillable="true">
                <xsd:complexType>
                    <xsd:simpleContent>
                        <xsd:extension base="xsd:string">
                            <xsd:attribute default="statute miles" name="units" use="optional">
                                <xsd:simpleType>
                                    <xsd:restriction base="xsd:string">
                                        <xsd:enumeration value="statute miles" />
                                        <xsd:enumeration value="meters" />
                                    </xsd:restriction>
                                </xsd:simpleType>
                            </xsd:attribute>
                        </xsd:extension>
                    </xsd:simpleContent>
                </xsd:complexType>
            </xsd:element>
        </xsd:sequence>
        <xsd:attribute name="coverage" use="optional">
            <xsd:simpleType>
                <xsd:restriction base="xsd:string">
                    <xsd:enumeration value="slight chance" />
                    <xsd:enumeration value="chance" />
                    <xsd:enumeration value="likely" />
                    <xsd:enumeration value="occasional" />
                    <xsd:enumeration value="definitely" />
                    <xsd:enumeration value="isolated" />
                    <xsd:enumeration value="scattered" />
                    <xsd:enumeration value="numerous" />
                    <xsd:enumeration value="patchy" />
                    <xsd:enumeration value="areas" />
                    <xsd:enumeration value="widespread" />
                    <xsd:enumeration value="periods of" />
                    <xsd:enumeration value="frequent" />
                    <xsd:enumeration value="intermittent" />
                    <xsd:enumeration value="none" />
                </xsd:restriction>
            </xsd:simpleType>
        </xsd:attribute>
        <xsd:attribute name="weather-type" use="optional">
            <xsd:simpleType>
                <xsd:restriction base="xsd:string">
                    <xsd:enumeration value="freezing drizzle" />
                    <xsd:enumeration value="freezing rain" />
                    <xsd:enumeration value="snow showers" />
                    <xsd:enumeration value="blowing snow" />
                    <xsd:enumeration value="blowing dust" />
                    <xsd:enumeration value="rain showers" />
                    <xsd:enumeration value="ice pellets" />
                    <xsd:enumeration value="frosts" />
                    <xsd:enumeration value="rain" />
                    <xsd:enumeration value="hail" />
                    <xsd:enumeration value="snow" />
                    <xsd:enumeration value="thunderstorms" />
                    <xsd:enumeration value="drizzle" />
                    <xsd:enumeration value="fog" />
                    <xsd:enumeration value="haze" />
                    <xsd:enumeration value="smoke" />
                </xsd:restriction>
            </xsd:simpleType>
        </xsd:attribute>
        <xsd:attribute name="intensity" use="optional">
            <xsd:simpleType>
                <xsd:restriction base="xsd:string">
                    <xsd:enumeration value="very light" />
                    <xsd:enumeration value="light" />
                    <xsd:enumeration value="moderate" />
                    <xsd:enumeration value="heavy" />
                    <xsd:enumeration value="none" />
                </xsd:restriction>
            </xsd:simpleType>
        </xsd:attribute>
        <xsd:attribute name="additive" use="optional">
            <xsd:simpleType>
                <xsd:restriction base="xsd:string">
                    <xsd:enumeration value="and" />
                    <xsd:enumeration value="or" />
                </xsd:restriction>
            </xsd:simpleType>
        </xsd:attribute>
        <xsd:attribute name="qualifier" use="optional">
            <xsd:simpleType>
                <xsd:restriction base="xsd:string">
                    <xsd:annotation>
                        <xsd:documentation xml:lang="en">
                                                                  This expression enforces a comma-delimited list
                                                               </xsd:documentation>
                    </xsd:annotation>
                    <xsd:pattern value="(\p{L}* ?\p{L}*)?(,\p{L}+ ?\p{L}*)*" />
                </xsd:restriction>
            </xsd:simpleType>
        </xsd:attribute>
    </xsd:complexType>
</xsd:element>