<xs:attributeGroup name="UniqueID_Group">
    <xs:annotation>
        <xs:documentation xml:lang="en">Provides unique identification information.</xs:documentation>
    </xs:annotation>
    <xs:attribute name="URL" type="xs:anyURI">
        <xs:annotation>
            <xs:documentation xml:lang="en">URL that identifies the location associated with the record identified by the UniqueID.</xs:documentation>
        </xs:annotation>
    </xs:attribute>
    <xs:attribute name="Type" type="OTA_CodeType" use="required">
        <xs:annotation>
            <xs:documentation xml:lang="en">A reference to the type of object defined by the UniqueID element. Refer to OTA Code List Unique ID Type (UIT).</xs:documentation>
        </xs:annotation>
    </xs:attribute>
    <xs:attribute name="Instance" type="StringLength1to32">
        <xs:annotation>
            <xs:documentation xml:lang="en">The identification of a record as it exists at a point in time. An instance is used in update messages where the sender must assure the server that the update sent refers to the most recent modification level of the object being updated.</xs:documentation>
        </xs:annotation>
    </xs:attribute>
    <xs:attributeGroup ref="ID_Group">
        <xs:annotation>
            <xs:documentation xml:lang="en">Used to provide a required unique identifier.</xs:documentation>
        </xs:annotation>
    </xs:attributeGroup>
    <xs:attribute name="ID_Context" type="StringLength1to32" use="optional">
        <xs:annotation>
            <xs:documentation xml:lang="en">Used to identify the source of the identifier (e.g., IATA, ABTA).</xs:documentation>
        </xs:annotation>
    </xs:attribute>
</xs:attributeGroup>