Web Service as Datasource for a Report

hello.

current situation:

CR2008 (12.3.0.601)

webservice is created.

webservice is bound as datasource in CR.

report creation works fine.

but:

i would like to provide key information for the tables specified in WS-XSD.

something like (marked with '->'):

<xsd:complexType name="someTableRowType">
  <xsd:sequence>
    <xsd:element name="numberColumnInSomeTable" type="xsd:int" minOccurs="1" maxOccurs="1">
->    <xsd:attribute name="key" type="xsd:string" fixed="true"/>
    </xsd:element>
    <xsd:element name="stringColumnInSomeTable" type="xsd:string" minOccurs="1" maxOccurs="1" />
  </xsd:sequence>
</xsd:complexType>

<xsd:complexType name="someTableType">
  <xsd:sequence>
    <xsd:element name="someTableRowType" type="xsd:string" minOccurs="0" maxOccurs="unbound" />
  </xsd:sequence>
</xsd:complexType>

// and then:

<xsd:complexType name="someOtherTableRowType">
  <xsd:sequence>
    <xsd:element name="numberColumnInSomeOtherTable" type="xsd:int" minOccurs="1" maxOccurs="1">
->   <xsd:attribute name="references" type="xsd:string" use="required"/>
    </xsd:element>
    <xsd:element name="stringColumnInSomeOtherTable" type="xsd:string" minOccurs="1" maxOccurs="1" />
  </xsd:sequence>
</xsd:complexType>

<xsd:complexType name="someOtherTableType">
  <xsd:sequence>
    <xsd:element name="someOtherTableRowType" type="xsd:string" minOccurs="0" maxOccurs="unbound" />
  </xsd:sequence>
</xsd:complexType>

i am looking for the keywords for "key" and "references". is there something like that? or an other posibility exist?