<xsd:attribute name="type" use="required">
    <xsd:simpleType>
        <xsd:restriction base="xsd:string">
            <xsd:enumeration value="maximum" />
            <xsd:enumeration value="minimum" />
            <xsd:enumeration value="hourly" />
            <xsd:enumeration value="rtma-hourly" />
            <xsd:enumeration value="dew point" />
            <xsd:enumeration value="rtma-dew point" />
            <xsd:enumeration value="heat index" />
            <xsd:enumeration value="wind chill" />
            <xsd:enumeration value="apparent" />
            <xsd:enumeration value="8-14 day anomolies" />
            <xsd:enumeration value="monthly anomolies" />
            <xsd:enumeration value="seasonal anomolies" />
        </xsd:restriction>
    </xsd:simpleType>
</xsd:attribute>