<xs:attribute name="SourceType" use="optional">
    <xs:annotation>
        <xs:documentation xml:lang="en">Information describing the point of sale.</xs:documentation>
    </xs:annotation>
    <xs:simpleType>
        <xs:restriction base="xs:NMTOKEN">
            <xs:enumeration value="NormalTransaction">
                <xs:annotation>
                    <xs:documentation xml:lang="en">Agent representation (for example, a ticket office).</xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="MailOrPhoneOrder">
                <xs:annotation>
                    <xs:documentation xml:lang="en">The source of the purchase request is a mail or phone order.</xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="UnattendedTerminal">
                <xs:annotation>
                    <xs:documentation xml:lang="en">The source of the purchase request is an unattended terminal such as a kiosk or ATM.</xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="MerchantIsSuspicious">
                <xs:annotation>
                    <xs:documentation xml:lang="en">Indicates that the merchant requesting the credit seems to be suspicious or fraudulent.</xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="eCommerceSecuredTransaction">
                <xs:annotation>
                    <xs:documentation xml:lang="en">Indicates an e-comerce transaction provided over a secure channel. For example, SSL (secure sockets layer).</xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="eCommerceUnsecuredTransaction">
                <xs:annotation>
                    <xs:documentation xml:lang="en">Indicates an e-comerce transaction provided over an unsecured channel. For example HTTP.</xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="InFlightAirPhone">
                <xs:annotation>
                    <xs:documentation xml:lang="en">The purchase request is made from an in flight air phone.</xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="CID_NotLegible">
                <xs:annotation>
                    <xs:documentation xml:lang="en">The customer identification number cannot be read.</xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="CID_NotOnCard">
                <xs:annotation>
                    <xs:documentation xml:lang="en">There is no customer identification number on the card.</xs:documentation>
                </xs:annotation>
            </xs:enumeration>
        </xs:restriction>
    </xs:simpleType>
</xs:attribute>