Data Type for length specification; recommended data type for values = double

<?xml version="1.0" encoding="utf-16"?>
<xsd:simpleType name="IRlength">
    <xsd:annotation>
        <xsd:documentation>Data Type for length specification; recommended data type for values = double</xsd:documentation>
    </xsd:annotation>
    <xsd:restriction base="xsd:string">
        <xsd:maxLength value="5" />
        <xsd:minLength value="1" />
        <xsd:enumeration value="mm">
            <xsd:annotation>
                <xsd:documentation>Metric Millimeters acc. to ISO..... 1mm = 0,001m</xsd:documentation>
            </xsd:annotation>
        </xsd:enumeration>
        <xsd:enumeration value="cm">
            <xsd:annotation>
                <xsd:documentation>Metric Centimeters acc. to ISO..... 1 cm = 0,01 m</xsd:documentation>
            </xsd:annotation>
        </xsd:enumeration>
        <xsd:enumeration value="m">
            <xsd:annotation>
                <xsd:documentation>Metric Meters (Metric Base unit) acc. to ISO.....</xsd:documentation>
            </xsd:annotation>
        </xsd:enumeration>
        <xsd:enumeration value="km">
            <xsd:annotation>
                <xsd:documentation>Metric Kilometers acc. to ISO..... 1km = 1000m</xsd:documentation>
            </xsd:annotation>
        </xsd:enumeration>
        <xsd:enumeration value="ft">
            <xsd:annotation>
                <xsd:documentation>Feet according to ..... 1ft = ........ m</xsd:documentation>
            </xsd:annotation>
        </xsd:enumeration>
    </xsd:restriction>
</xsd:simpleType>