<xsd:element name="Substance" minOccurs="0" maxOccurs="unbounded">
    <xsd:annotation>
        <xsd:documentation>Details regarding each substance identified within the requested test.</xsd:documentation>
    </xsd:annotation>
    <xsd:complexType>
        <xsd:sequence>
            <xsd:element name="SubstanceType" type="SubstanceTypeType">
                <xsd:annotation>
                    <xsd:documentation>Name of the substance being tested for.</xsd:documentation>
                </xsd:annotation>
            </xsd:element>
            <xsd:element name="Results" type="DrugTestResultType">
                <xsd:annotation>
                    <xsd:documentation>Results of the test. i.e. Negative, adulterated.</xsd:documentation>
                </xsd:annotation>
            </xsd:element>
            <xsd:element name="Concentration" type="xsd:string" minOccurs="0">
                <xsd:annotation>
                    <xsd:documentation>Amount of drug in a unit volume of biological fluid expressed as weight/volume. Urine concentrations are expressed in nanogram/milliliter, as micrograms/milliliter or milligrams/liter.</xsd:documentation>
                </xsd:annotation>
            </xsd:element>
        </xsd:sequence>
    </xsd:complexType>
</xsd:element>