<[
        <!ELEMENT Message (AvailabilityWebRequestResponse)*>
        <!ATTLIST Message
                source CDATA #REQUIRED
                target CDATA #REQUIRED
                type CDATA #REQUIRED>
        <!ELEMENT AvailabilityWebRequestResponse (#PCDATA)>
        <!ATTLIST AvailabilityWebRequestResponse
                company CDATA #REQUIRED
                company_description CDATA #REQUIRED
                message CDATA #REQUIRED>
        ]>